THE HUNTING WASPS
THE WORKS OF J. H. FABRE
‘The Insects’ Homer’
Maurice Maeterlinck.
[THE LIFE OF THE FLY]
Translated by
Alexander Teixeira de Mattos, F.Z.S.
6s. net.
[THE LIFE OF THE SPIDER]
Translated by
Alexander Teixeira de Mattos, F.Z.S.
With a Preface by Maurice Maeterlinck.
6s. net.
[THE MASON-BEES]
Translated by
Alexander Teixeira de Mattos, F.Z.S.
6s. net.
[BRAMBLE-BEES AND OTHERS]
Translated by
Alexander Teixeira de Mattos, F.Z.S.
6s. net.
LONDON: HODDER AND STOUGHTON
THE WORKS OF J. H. FABRE
THE
HUNTING WASPS
BY
J. HENRI FABRE
Translated by
ALEXANDER TEIXEIRA DE MATTOS, F.Z.S.
HODDER AND STOUGHTON
LONDON NEW YORK TORONTO
Copyright in the United States of America,
1916, by Dodd, Mead & Co. [[v]]
Translator’s Note
Henri Fabre’s essays on Wasps will fill three volumes in all, of which this is the first. The others will be entitled The Mason-Wasps and More Hunting Wasps. The former will include the chapters on the Common or Social Wasp.
The first seventeen chapters of the present book appeared some years ago, wholly or in part, in a version of vol. i. of the Souvenirs Entomologiques prepared by the author of Mademoiselle Mori for Messrs. Macmillan and Co., by arrangement with whom I am now permitted to retranslate and republish them for the purpose of this collected and definite edition of Fabre’s entomological works. Of the remainder, ‘The Modern Theory of Instinct’ first saw the light in the English Review, and ‘An Unknown Sense,’ in an abbreviated form, in the Daily Mail.
It is a pleasure once more to express my thanks to Miss Frances Rodwell, who, as usual, [[vi]]has rendered me much valuable assistance, and to Mr. Geoffrey Meade-Waldo, of the Natural History Museum, who has been kind enough to set me right on many an entomological point.
Alexander Teixeira de Mattos.
Chelsea, 1916. [[vii]]
Contents
PAGE
CHAPTER I
[THE BUPRESTIS-HUNTING CERCERIS] 1
CHAPTER II
CHAPTER III
CHAPTER IV
CHAPTER V
CHAPTER VI
[THE LARVA AND THE NYMPH] 86 [[viii]]
CHAPTER VII
CHAPTER VIII
CHAPTER IX
CHAPTER X
[THE IGNORANCE OF INSTINCT] 174
CHAPTER XI
[AN ASCENT OF MONT VENTOUX] 196
CHAPTER XII
[THE TRAVELLERS] 215
CHAPTER XIII
[THE AMMOPHILÆ] 231
CHAPTER XIV
[THE BEMBEX] 251 [[ix]]
CHAPTER XV
[THE FLY-HUNT] 271
CHAPTER XVI
[A PARASITE OF THE BEMBEX. THE COCOON] 284
CHAPTER XVII
CHAPTER XVIII
CHAPTER XIX
CHAPTER XX
[THE MODERN THEORY OF INSTINCT] 354
[APPENDIX] 379
Chapter i
THE BUPRESTIS-HUNTING CERCERIS
There are for each one of us, according to his turn of mind, certain books that open up horizons hitherto undreamed of and mark an epoch in our mental life. They fling wide the gates of a new world wherein our intellectual powers are henceforth to be employed; they are the spark which lights the fuel on a hearth doomed, without its aid, to remain indefinitely bleak and cold. And it is often chance that places in our hands those books which mark the beginning of a new era in the evolution of our ideas. The most casual circumstances, a few lines that happen somehow to come before our eyes, decide our future and plant us in the appointed groove.
One winter evening, when the rest of the household was asleep, as I sat reading beside a stove whose ashes were still warm, my book made me forget for a while the cares of the morrow: those heavy cares of a poor professor of physics who, after piling up diplomas [[2]]and for a quarter of a century performing services of uncontested merit, was receiving for himself and his family a stipend of sixteen hundred francs, or less than the wages of a groom in a decent establishment. Such was the disgraceful parsimony of the day where education was concerned; such was the edict of our government red-tape: I was an irregular, the offspring of my solitary studies. And so I was forgetting the poverty and anxieties of a professor’s life, amid my books, when I chanced to turn over the pages of an entomological essay that had fallen into my hands I forget how.
It was a monograph by the then father of entomology, the venerable scientist Léon Dufour,[1] on the habits of a Wasp that hunted Buprestis-beetles. Certainly, I had not waited till then to interest myself in insects; from my early childhood I had delighted in Beetles, Bees, and Butterflies; as far back as I can remember, I see myself in ecstasy before the splendour of a Ground-beetle’s wing-cases or the wings of Papilio machaon, the Swallowtail. The fire was laid; the spark to kindle it was [[3]]absent. Léon Dufour’s essay provided that spark.
New lights burst forth: I received a sort of mental revelation. So there was more in science than the arranging of pretty Beetles in a cork box and giving them names and classifying them; there was something much finer: a close and loving study of insect life, the examination of the structure and especially the faculties of each species. I read of a magnificent instance of this, glowing with excitement as I did so. Some time after, aided by those lucky circumstances which he who seeks them eagerly is always able to find, I myself published an entomological article, a supplement to Léon Dufour’s. This first work of mine won honourable mention from the Institute of France and was awarded a prize for experimental physiology. But soon I received a far more welcome recompense, in the shape of a most eulogistic and encouraging letter from the very man who had inspired me. From his home in the Landes the revered master sent me a warm expression of his enthusiasm and urged me to go on with my studies. Even now, at that sacred recollection, my old eyes fill with happy tears. O fair days of illusion, of faith in the future, where are you now? [[4]]
I am sure that my readers will welcome an extract from the essay that formed the starting-point of my own researches, especially as this extract is necessary for the due understanding of what follows. I will therefore let the master speak for himself, abridging his words in parts:[2]
‘In all insect history, I can think of no more curious, no more extraordinary fact than that which I am about to describe to you. It concerns a species of Cerceris who feeds her family on the most sumptuous species of the genus Buprestis. Allow me to make you share the vivid impressions which I owe to my study of this Hymenopteron’s habits.
‘In July 1839, a friend living in the country sent me two specimens of Buprestis bifasciata, an insect at that time new to my collection, informing me that a kind of Wasp that was carrying one of these pretty Beetles had let it fall on his coat and that, a few moments later, a similar Wasp had dropped another on the ground.
‘In July 1840, I was visiting my friend’s house professionally and reminded him of his capture of the year before and asked for details of the circumstances that accompanied it. [[5]]The identity of the season and place made me hope to make a similar capture myself; but the weather that day was overcast and chilly; and therefore but few Wasps had ventured out. Nevertheless, we made a tour of inspection in the garden; and, seeing nothing coming, I thought of looking on the ground for the homes of Burrowing Hymenoptera.
‘My attention was attracted by a small heap of sand freshly thrown up and forming a sort of tiny mole-hill. On raking it, I saw that it masked the opening of a shaft running some way down. With a spade we carefully turned over the soil and soon saw the glittering wing-cases of the coveted Buprestis lying scattered around. Presently I discovered not only isolated and fragmentary wing-cases, but a whole Buprestis, then three or four of them, displaying their emerald and gold. I could not believe my eyes.
‘But this was only a prelude to the feast. In the chaos of rubbish produced by the exhumation, a Wasp appeared and fell into my hands: it was the kidnapper of the Buprestes, trying to escape from among her victims. In this burrowing insect I recognized an old acquaintance, a Cerceris whom I have found hundreds of times, both in Spain and round about Saint-Sever. [[6]]
‘My ambition was far from satisfied. It was not enough for me to identify the kidnapper and her victim: I wanted the larva, the sole consumer of those rich provisions. After exhausting this first vein of Buprestes, I hastened to make fresh excavations and, planting my spade more carefully still, I at last succeeded in discovering two larvæ which crowned the good fortune of this campaign. In less than an hour I ransacked the haunts of three Cerceres; and my booty was some fifteen whole Buprestes, with fragments of a still larger number. I calculated, keeping, I believe, well within the mark, that this particular garden contained five-and-twenty nests, making an enormous total of buried Buprestes. What must it be, I thought, in places where in a few hours I have caught on the garlic-flowers as many as sixty Cerceres, whose nests were apparently in the neighbourhood and no doubt victualled just as abundantly? And so my imagination, never going beyond the bounds of probability, showed me underground, within a small radius, Buprestis fasciata by the thousand, whereas, during the thirty years and upwards that I have been studying the entomology of this district, I never discovered a single one in the open.
‘Once only, perhaps twenty years ago, I found the abdomen of this insect, together [[7]]with its wing-cases, stuck in a hole in an old oak. This fact was illuminating. By informing me that the larva of Buprestis fasciata must live in the wood of the oak, it completely explained why this Beetle is so common in a district which has none but oak-forests. As Cerceris bupresticida is rare in the clay hills of such districts, as compared with the sandy plains thickly planted with the maritime pine, it became an interesting question to know whether this Wasp, when she inhabits the pine country, victuals her nest in the same way as in the oak country. I had a strong presumption that this was not the case; and you will soon see, not without surprise, what exquisite entomological discrimination our Cerceris displays in her choice of the numerous species of the genus Buprestis.
‘We will therefore hasten to the pine region to reap new delights. The field to be explored is the garden of a country-house standing amid forests of maritime pines. One soon recognized the dwellings of the Cerceris; they had been made solely in the main paths, where the firm, compact soil offered the Burrowing Hymenopteron a solid foundation for the construction of her subterranean abode. I inspected some twenty, I may say, by the sweat of my brow. It is a very laborious sort of undertaking, for [[8]]the nests, and consequently the provisions, are not found at less than a foot below the surface. It becomes necessary, therefore, lest they should be damaged, to begin by inserting a grass-stalk, serving as a landmark and a guide, into the Cerceris’ gallery and next to invest the place with a square of trenches, some seven or eight inches from the orifice or the landmark. The sapping must be done with a garden-spade, so that the central clod can be completely detached on every side and raised in one piece, which we turn over on the ground and then break up carefully. This was the method that answered with me.
‘You would have shared our enthusiasm, my friend, at the sight of the beautiful specimens of Buprestes which this original method of treasure-hunting disclosed, one after the other, to our eager gaze. You should have heard our exclamations each time that the mine was turned upside down and new glories stood revealed, rendered more brilliant still by the blazing sun; or when we discovered, here, larvæ of all ages fastened to their prey, there, the cocoons of those larvæ all encrusted with copper, bronze, and emerald. I who had been studying insects at close quarters for three or four decades—alas!—had never witnessed such a lovely sight nor enjoyed so great a treat. It [[9]]only needed your presence to double our delight. Our ever-increasing admiration was devoted by turns to those brilliant Beetles and to the marvellous discernment, the astonishing sagacity of the Cerceris who had buried and stored them away. Will you believe it, of more than four hundred Beetles[3] that we dug up, there was not one but belonged to the old genus Buprestis! Not even the very smallest mistake had been made by the wise Wasp. What can we not learn from this intelligent industry in so tiny an insect! What value would not Latreille[4] have set upon this Cerceris’ support of the natural method!
‘We will now pass to the different manœuvres of the Cerceris for establishing and victualling her nests. I have already said that she chooses ground with a firm, compact, and smooth surface; I will add that this ground must be dry and fully exposed to the sun. She reveals in this choice an intelligence, or, if you prefer, an instinct, which one might be tempted to consider the result of experience. Loose earth or [[10]]a merely sandy soil would doubtless be much easier to dig; but then how is she to get an aperture that will remain open for goods to pass in and out, or a gallery whose walls will not constantly be liable to fall in, to lose their shape, to be blocked after a few days of rain? Her choice therefore is both sensible and nicely calculated.
‘Our Burrowing Wasp digs her gallery with her mandibles and her front tarsi, which are furnished for this purpose with stiff spikes that perform the office of rakes. The orifice must not only have the diameter of the miner’s body: it must also be able to admit a capture of large bulk. It is an instance of admirable foresight. As the Cerceris goes deeper into the earth, she casts out the rubbish: this forms the heap which I likened above to a tiny mole-hill. The gallery is not perpendicular, for then it would inevitably become blocked up, owing either to the wind or to other causes. Not far from where it starts, it forms an angle; its length is seven or eight inches. At the end of the passage the industrious mother establishes the cradles of her offspring. These consist of five separate cells, independent of one another, arranged in a semicircle and hollowed into the shape and nearly the size of an olive. Inside, they are polished and firm. Each of them is [[11]]large enough to contain three Buprestes, which form the usual allowance for each larva. The mother lays an egg in the middle of the three victims and then stops up the gallery with earth, so that, when the victualling of the whole brood is finished, the cells no longer communicate with the outside.
‘Cerceris bupresticida must be a dexterous, daring, and skilful huntress. The cleanliness and freshness of the Buprestes whom she buries in her lair incline one to believe that she must seize these Beetles at the moment when they are leaving the wooden galleries in which their final metamorphosis has taken place. But what inconceivable instinct urges her, a creature that lives solely on the nectar of flowers, to procure, in the face of a thousand difficulties, animal food for carnivorous children which she will never see, and to take up her post on utterly dissimilar trees, which conceal deep down in their trunks the insects destined to become her prey? What yet more inconceivable entomological judgment lays down the strict law that she shall confine herself in the choice of her victims to a single generic group and capture specimens differing greatly among themselves in size, shape, and colour? For observe, my friend, how slight the resemblance is between Buprestis biguttata, with a long, slender body [[12]]and a dark colour; B. octoguttata, oval-oblong, with great patches of a beautiful yellow on a blue or green ground; and B. micans, who is three or four times the size of B. biguttata and glitters with a metallic lustre of a fine golden green.
‘There is another very singular fact about the manœuvres of our Buprestis-slayer. The buried Buprestes, like those whom I have seized in the grasp of their kidnappers, are always deprived of any sign of life; in a word, they are decidedly dead. I was surprised to remark that, no matter when these corpses were dug up, they not only preserved all their freshness of colouring, but their legs, antennæ, palpi, and the membranes uniting the various parts of the body remained perfectly supple and flexible. There was no mutilation, no apparent wound to be seen. One might at first believe the reason, in the case of the buried ones, to be due to the coolness of the bowels of the earth, in the absence of air and light; and, in the case of those taken from the kidnappers, to the very recent date of their death. But please observe that, at the time of my explorations, after placing the numerous exhumed Buprestes in separate screws of paper, I often left them in their little bags for thirty-six hours before pinning them out. Well, notwithstanding the dryness of the air and the burning July heat, [[13]]I always found the same flexibility in their joints. Nay more: I have dissected several of them, after that lapse of time, and their viscera were as perfectly preserved as if I had used my scalpel on the insects’ live entrails. Now long experience has taught me that, even in a Beetle of this size, when twelve hours have passed after death in summer, the internal organs become either dried up or putrefied, so that it is impossible to make sure of their form or structure. There is some special circumstance about the Buprestes killed by the Cerceres that saves them from desiccation and putrefaction for a week and perhaps two. But what is this circumstance?’
To explain this wonderful preservation of the tissues which makes of an insect smitten for many weeks past with a corpse-like inertness a piece of game which does not even go high and which, during the greatest heat of summer, keeps as fresh as at the moment of its capture, the able historian of the Buprestis-huntress surmises the presence of an antiseptic fluid, acting similarly to the preparations used for preserving anatomical specimens. This fluid, he suggests, can be nothing but the poison of the Wasp, injected into the victim’s body. A tiny drop of the venomous liquid accompanying [[14]]the sting, the needle destined for the inoculation, would therefore serve as a kind of brine or pickle to preserve the meat on which the larva is to feed. But how immensely superior to our own pickling processes is that of the Wasp! We salt, or smoke, or tin foodstuffs which remain fit to eat, it is true, but which are very far indeed from retaining the qualities which they possessed when fresh. Tins of sardines soaked in oil, Dutch smoked herrings, codfish reduced to hard slabs by salt and sun: which of these can compare with the same fish supplied to the cook, so to speak, all alive and kicking? In the case of flesh-meat, things are even worse. Apart from salting and curing, we have nothing that can keep a piece of meat fit for consumption for even a fairly short period.
Nowadays, after a thousand fruitless attempts in the most varied directions, we equip special ships at great cost; and these ships, fitted with a powerful refrigerating-plant, bring us the flesh of sheep and oxen slaughtered in the South American pampas, frozen and preserved from decomposition by the intense cold. How much more excellent is the Cerceris’ method, so swift, so inexpensive, and so efficacious! What lessons can we not learn from her transcendental chemistry! With an imperceptible drop of her poison-fluid, she straightway renders [[15]]her prey incorruptible! Incorruptible, did I say? It is much more than that! The game is brought to a condition which prevents desiccation, leaves the joints supple, keeps all the organs, both internal and external, in their pristine freshness, and, in short, places the sacrificed insect in a state that differs from life only by its corpse-like immobility.
This is the theory that satisfied Léon Dufour, as he contemplated the incomprehensible marvel of those dead Buprestes proof against corruption. A preserving-fluid, incomparably superior to aught that human science can produce, explains the mystery. He, the master, the ablest of them all, an expert in the niceties of anatomy; he who, with magnifying-glass and scalpel, examined the whole entomological series, leaving no nook or corner unexplored; he, in short, for whom insect organism possessed no secrets can think of nothing better than an antiseptic fluid to give at least the semblance of an explanation of a fact that leaves him confounded. I crave permission to emphasize this comparison between animal instinct and the reasoning power of the sage in order the better to bring to light, in due season, the overwhelming superiority of the former.
I will add but a few words to the history of the Buprestis-hunting Cerceris. This Wasp, [[16]]who is common in the Landes, as her historian tells us, appears to be very rarely found in the department of Vaucluse. I have met her only at long intervals, in autumn—and then only isolated specimens—on the spiny heads of the field eryngo (Eryngium campestre), in the neighbourhood either of Avignon or of Orange and Carpentras. In this last spot, so favourable to the work of the Burrowing Wasps owing to its sandy soil of Molasse formation, I have had the good fortune, not to witness the exhumation of such entomological treasures as Léon Dufour describes, but to find some old nests which I attribute without hesitation to the Buprestis-huntress, basing my opinion upon the shape of the cocoons, the nature of the provisioning, and the presence of the Wasp in the neighbourhood. These nests, dug in the heart of a very crumbly sandstone, known in the district as safre, were crammed with remains of Beetles, remains easily recognized and consisting of detached wing-cases, gutted corselets and entire legs. Now these broken victuals of the larva’s banquet all belonged to a single species; and that species was once more a Buprestis, the Double-lined Buprestis (Sphenoptera geminata).[5] Thus from [[17]]the west to the east of France, from the department of the Landes to that of Vaucluse, the Cerceris remains faithful to her favourite prey; longitude makes no difference to her predilections; a huntress of Buprestes among the maritime pines of the sand-dunes along the coast remains a huntress of Buprestes among the olive-trees and evergreen oaks of Provence. She changes the species according to place, climate, and vegetation, which alter the nature of the insect population so greatly; but she never departs from her favoured genus, the genus Buprestis. What can her reason be? That is what I shall try to show. [[18]]
[1] Léon Dufour (1780–1865) was an army surgeon who served with distinction in several campaigns and subsequently practised as a doctor in the Landes. He attained great eminence as a naturalist. Cf. The Life of the Spider, by J. Henri Fabre, translated by Alexander Teixeira de Mattos, chap, i.—Translator’s Note. [↑]
[2] For the complete monograph, cf. Annales des sciences naturelles: Series II., vol. xv.—Author’s Note. [↑]
[3] The 450 Buprestes unearthed belong to the following species: Buprestis octoguttata; B. fasciata; B. pruni; B. tarda; B. biguttata; B. micans; B. flavomaculata; B. chrysostigma; and B. novemmaculata.—Author’s Note. [↑]
[4] Pierre André Latreille (1762–1833), a French naturalist who was one of the founders of entomological science.—Translator’s Note. [↑]
[5] The Beetle known to Fabre as Sphenoptera geminata, Uliger, is now considered identical with S. lineola, Herbst, which was known many years earlier.—Translator’s Note. [↑]
Chapter ii
THE GREAT CERCERIS
With my memory full of the prowess of the Buprestis-huntress, I watched for an opportunity to observe in my turn the labours of the Cerceres; and I watched to such good purpose that I ended by being successful. True, the Wasp was not the one celebrated by Léon Dufour, with her sumptuous victuals whose remains, when unearthed, suggest the dust of some nugget broken by the gold-miner’s pick: it was a kindred species, a gigantic brigand who contents herself with humbler prey; in short, it was Cerceris tuberculata or C. major, the largest and most powerful of the genus.
The last fortnight in September is the time when our Burrowing Wasp digs her lairs and buries in their depths the victim destined for her grubs. The site of the home, always selected with discrimination, is subject to those mysterious laws which differ in different species but are invariable throughout any one species. Léon Dufour’s Cerceris requires a level, well-trodden, [[19]]compact soil, such as that of a path, to prevent the possibility of landslips and other damage which would ruin her gallery at the first shower of rain. Ours, on the contrary, is not very particular about the nature of her soil, but must have that soil vertical. With this slight architectural modification, she avoids most of the dangers that might threaten her gallery; and consequently she digs her burrows indifferently in a loose and slightly clayey soil and in the soft sand of the Molasse formation, which makes the work of excavation much easier. The only indispensable condition appears to be that the earth should be dry and exposed to the sun’s rays for the best part of the day. It is therefore in the steep roadside banks, in the sides of the ravines hollowed by the rains in the sandstone, that our Wasp elects to establish her home. These conditions are common in the neighbourhood of Carpentras, in the part known as the Hollow Road; and it is here that I have observed Cerceris tuberculata in her largest numbers and that I gathered most of my facts relating to her history.
The choice of this vertical site is not enough for her: other precautions are taken to guard against the inevitable rains of the season, which is already far advanced. If there be [[20]]some bit of hard sandstone projecting like a ledge, if there be naturally hollowed in the ground some hole large enough to put one’s fist in, it will be under that shelter or in this cavity that she contrives her gallery, thus adding a natural vestibule to the edifice of her own construction. Though no sort of communism exists among them, these insects nevertheless like to associate in small numbers; and I have always observed their nests in groups of about ten at least, with the orifices, which are usually pretty far apart, sometimes close enough to touch one another.
On a bright, sunny day it is wonderful to watch the different operations of these industrious miners. Some patiently remove with their mandibles a few bits of gravel from the bottom of the pit and push the heavy mass outside; others, scraping the walls of the corridor with the sharp rakes of their tarsi, collect a heap of rubbish which they sweep out backwards and send streaming down the sides of the slopes in a long thread of dust. It was these periodical billows of sand discharged from the galleries in process of building that betrayed the presence of my first Cerceres to me and enabled me to discover their nests. Others, either because they are tired or because they have finished their hard task, seem to rest and [[21]]polish their antennæ and wings under the natural eaves that most frequently protect their dwelling; or else they remain motionless at the mouth of the hole, merely showing their wide, square faces, striped black and yellow. Others, lastly, flit gravely humming on the neighbouring kermes-oak-bushes, where the males, always on the watch near the burrows in course of construction, are not slow to join them. Couples form, often disturbed by the arrival of a second male, who strives to supplant the happy possessor. The humming becomes threatening, brawls take place and often the two males roll in the dust until one of them acknowledges the superiority of his rival. Near by, the female awaits the outcome of the struggle with indifference; she finally accepts the male whom the chances of the contest bestow upon her; and the couple fly out of sight in search of peace and quiet on some distant brushwood. Here the part played by the males ends. Only half the size of the females and nearly as numerous, they prowl all around the burrows, but never enter and never take part in the laborious mining operations nor in the perhaps even more difficult hunting expeditions by means of which the cells are to be stocked.
The galleries are ready in a few days, especially [[22]]as those of the previous year are employed with the aid of a few repairs. The other Cerceres, so far as I know, have no fixed home, no family inheritance handed down from generation to generation. A regular gipsy tribe, they settle singly wherever the chances of their vagrant life may lead them, provided that the soil suits them. But the Great Cerceris is faithful to her household gods. The overhanging blade of sandstone that sheltered her predecessors is adopted by her in her turn; she digs in the same layer of sand wherein her forbears dug; and, adding her own labours to those which went before, she obtains deep retreats that are not always easy of inspection. The diameter of the galleries is wide enough to admit a man’s thumb; and the insect moves about in them readily, even when laden with the prey which we shall see it capture. Their direction, at first horizontal to a depth of four to eight inches, describes a sudden bend and dips more or less obliquely now to this side, now to that. With the exception of the horizontal part and the bend, the direction of the rest of the tube seems to be regulated by the difficulties presented by the ground, as is proved by the twists and turns observed in the more distant portion. The total length of the shaft attains as much as eighteen inches. At the [[23]]far end of the tube are the cells, few in number and each provisioned with five or six corpses of the Beetle order. But let us leave these building details and come to facts more capable of exciting our admiration.
The victim which the Cerceris chooses whereon to feed her grubs is a large-sized Weevil, Cleonus ophthalmicus. We see the kidnapper arrive heavily laden, carrying her victim between her legs, body to body, head to head, and plump down at some distance from her hole, to complete the rest of the journey without the aid of her wings. The Wasp is now dragging her prey in her mandibles up a vertical, or at least a very steep surface, productive of frequent tumbles which send kidnapper and kidnapped rolling helter-skelter to the bottom, but incapable of discouraging the indefatigable mother, who, covered with dirt and dust, ends by diving into the burrow with her booty, which she has not let go for a single moment. Whereas the Cerceris finds it far from easy to walk with such a burden, especially on ground of this character, it is a different matter when she is flying, which she does with a vigour that astonishes us when we consider that the sturdy little creature is carrying a prize almost as large as herself and heavier. I had the curiosity to compare the weight of the Cerceris and [[24]]her victim: the first turned the scale at 150 milligrammes;[1] the second averaged 250 milligrammes,[2] or nearly double.
These figures are eloquent of the powers of the huntress, nor did I ever weary of admiring the nimbleness and ease with which she resumed her flight, with the game between her legs, and rose to a height at which I lost sight of her whenever, tracked too close by my indiscretion, she resolved to flee in order to save her precious booty. But she did not always fly away; and I would then succeed, not without difficulty, lest I should hurt her, in making her drop her prey by worrying her and rolling her over. I would then seize the Weevil; and the Cerceris, thus despoiled, would hunt about here and there, enter her lair for a moment and soon come out again to fly off on a fresh chase. In less than ten minutes the skilled huntress had found a new victim, performed the murder and accomplished the rape, which I often allowed myself to turn to my own profit. Eight times in succession I have committed the same robbery at the expense of the same Wasp; eight times, with unshaken consistency, she has recommenced her fruitless expedition. Her patience outwore mine; and I [[25]]left her in undisturbed possession of her ninth capture.
By this means, or by violating cells already provisioned, I procured close upon a hundred Weevils; and, notwithstanding what I was entitled to expect from what Léon Dufour has told us of the habits of the Buprestis-hunting Cerceris, I could not repress my surprise at the sight of the singular collection which I had made. Whereas the Buprestis-slayer, while confining herself to one genus, passes indiscriminately from one species to another, the more exclusive Great Cerceris preys invariably on the same species, Cleonus ophthalmicus. When going through my bag I came upon but one exception, and even that belonged to a kindred species, Cleonus alternans, a species which I never saw again in my frequent visits to the Cerceris. Later researches supplied me with a second exception, in the shape of Bothynoderus albidus; and that is all. Is this predilection for a single species adequately explained by the greater flavour and succulence of the prey? Do the grubs find in this monotonous diet juices which suit them and which they would not find elsewhere? I do not think so; and, if Léon Dufour’s Cerceris hunts every sort of Buprestis without distinction, this is doubtless because all the Buprestes possess the same [[26]]nutritive properties. But this must be generally the case with the Weevils also: their nourishing qualities must be identical; and then this surprising choice becomes only a question of size and consequently of economy of labour and time. Our Cerceris, the mammoth of her race, tackles the Ophthalmic Cleonus by preference because this Weevil is the largest in our district and perhaps also the commonest. But, if her favourite prey should fail, she must fall back upon other species, even though they be smaller, as is proved by the two exceptions stated.
Besides, she is far from being the only one to go hunting at the expense of the snouted clan, the Weevils. Many other Cerceres, according to their size, their strength and the accidents of the chase, capture Weevils varying infinitely in genus, species, shape, and dimensions. It has long been known that Cerceris arenaria feeds her grubs on similar provisions. I myself have encountered in her lairs Sitona lineata, S. tibialis, Cneorinus hispidus, Brachyderes gracilis, Geonemus flabellipes and Otiorhynchus maleficus. Cerceris aurita is known to make her booty of Otiorhynchus raucus and Phynotomus punctatus. The larder of Cerceris Ferreri has shown me the following: Phynotomus murinus, P. punctatus, Sitona lineata, Cneorinus hispidus, Rhynchites [[27]]betuleti. The last, who rolls vine-leaves in the shape of cigars, is sometimes a superb steel-blue and more ordinarily shines with a splendid golden copper. I have found as many as seven of these brilliant insects victualling a single cell; and the gaudiness of the little subterranean heap might almost stand comparison with the jewels buried by the Buprestis-huntress. Other species, notably the weaker, go in for lesser game, whose small size is atoned for by larger numbers. Thus Cerceris quadricincta stacks quite thirty specimens of Apion gravidum in each of her cells, without disdaining on occasion such larger Weevils as Sitona lineata and Phynotomus murinus. A similar provision of small species falls to the share of Cerceris labiata. Lastly, the smallest Cerceris in my district, Cerceris Julii,[3] chases the tiniest Weevils, Apion gravidum and Bruchus granarius, victims proportioned to the diminutive huntress. To finish with this list of game, let us add that a few Cerceres observe other gastronomic laws and raise their families on Hymenoptera. One of these is Cerceris ornata. We will dismiss these tastes as foreign to the subject in hand.
Of the eight species then of Cerceres whose provisions consist of Beetles, seven adopt a diet [[28]]of Weevils and one a diet of Buprestes. For what singular reasons are the depredations of these Wasps confined to such narrow limits? What are the motives for this exclusive choice? What inward likeness can there be between the Buprestes and the Weevils, outwardly so entirely dissimilar, that they should both become the food of kindred carnivorous grubs? Beyond a doubt, there are differences of flavour between this victim and that, nutritive differences which the larvæ are well able to appreciate; but some graver reason must overrule all such gastronomic considerations and cause these curious predilections.
After all the admirable things that have been said by Léon Dufour upon the long and wonderful preservation of the insects destined for the flesh-eating larvæ, it is almost needless to add that the Weevils, both those whom I dug up and those whom I took from between the legs of their kidnappers, were always in a perfect state of preservation, though deprived for ever of the power of motion. Freshness of colour, flexibility of the membranes and the lesser joints, normal condition of the viscera: all these combine to make you doubt that the lifeless body before your eyes is really a corpse, all the more as even with the magnifying-glass it is impossible to perceive the smallest wound; [[29]]and, in spite of yourself, you are every moment expecting to see the insect move and walk. Nay more: in a heat which, in a few hours, would have dried and pulverized insects that had died an ordinary death, or in damp weather, which would just as quickly have made them decay and go mouldy, I have kept the same specimens, both in glass tubes and paper bags, for more than a month, without precautions of any kind; and, incredible though it may sound, after this enormous lapse of time the viscera had lost none of their freshness and dissection was as easily performed as though I were operating on a live insect. No, in the presence of such facts, we cannot speak of the action of an antiseptic and believe in a real death: life is still there, latent, passive life, the life of a vegetable. It alone, resisting yet a little while longer the all-conquering chemical forces, can thus preserve the structure from decomposition. Life is still there, except for movement; and we have before our eyes a marvel such as chloroform or ether might produce, a marvel which owes its origin to the mysterious laws of the nervous system.
The functions of this vegetative life are no doubt enfeebled and disturbed; but at any rate they are exercised in a lethargic fashion. I have as a proof the evacuation performed [[30]]by the Weevils normally and at intervals during the first week of this deep slumber, which will be followed by no awakening and which nevertheless is not yet death. It does not cease until the intestines are emptied of their contents, as shown by autopsy. Nor do the faint glimmers of life which the insect still manifests stop at that; and, though irritability of the organs seems annihilated for good, I have nevertheless succeeded in arousing slight signs of it. Having placed some recently exhumed and absolutely motionless Weevils in a bottle containing sawdust moistened with a few drops of benzine, I was not a little astonished to see their legs and antennæ moving a quarter of an hour later. For a moment I thought that I could recall them to life. Vain hope! Those movements, the last traces of a susceptibility about to be extinguished, soon cease and cannot be excited a second time. I have tried this experiment in some cases a few hours after the murderous blow, in others as late as three or four days after, and always with the same success. Still, the movement is feeble in proportion to the time that has elapsed since the fatal stroke. It always spreads from front to back: the antennæ first wave slowly to and fro; then the front tarsi tremble and take part in the oscillation; next the tarsi of the [[31]]second pair of legs and lastly those of the third pair hasten to do likewise. Once movement sets in, these different appendages execute their vibrations without any order, until the whole relapses into immobility, which happens more or less quickly. Unless the blow has been dealt quite recently, the motion of the tarsi extends no farther and the legs remain still.
Ten days after an attack I was unable to obtain the least vestige of susceptibility by the above process; and I then had recourse to the Voltaic battery. This method is more powerful and provokes muscular contractions and movements where the benzine-vapour fails. We have only therefore to apply the current of one or two Bunsen cells through the conductors of some slender needles. Thrusting the point of one under the farthest ring of the abdomen and the point of the other under the neck, we obtain, each time the current is established, not only a quivering of the tarsi, but a strong reflexion of the legs, which draw up under the abdomen and then straighten out when the current is turned off. These flutterings, which are very energetic during the first few days, gradually diminish in intensity and appear no more after a certain time. On the tenth day I have still obtained perceptible movements; on the fifteenth day the battery [[32]]was powerless to provoke them, despite the suppleness of the limbs and the freshness of the viscera. To effect a comparison, I subjected to the action of the Voltaic pile Beetles really dead, Cellar-beetles, Saperdæ and Lamiæ, asphyxiated with benzine or sulphuric acid gas. Two hours at most after the asphyxiation, it was impossible for me to provoke the movements so easily obtained in Weevils who have already for several days been in that curious intermediate state between life and death into which their formidable enemy plunges them.
All these facts are opposed to the idea of something completely dead, to the theory that we have here a veritable corpse which has become incorruptible by the action of a preservative fluid. They can be explained only by admitting that the insect is smitten in the very origin and mainspring of its movements; that its susceptibility, suddenly benumbed, dies out slowly, while the more tenacious vegetative functions die still more slowly and keep the intestines in a state of preservation for the space of time required by the larvæ.
The particular thing which it was most important to ascertain was the manner in which the murder is committed. It is quite evident that the chief part in this must be played by the Cerceris’ venom-laden sting. But where [[33]]and how does it enter the Weevil’s body, which is covered with a hard and well-riveted cuirass? In the various insects pierced by the assassin’s dart, nothing, even under the magnifying-glass, betrayed her method. It became a matter, therefore, of discovering the murderous manœuvres of the Wasp by direct observation, a problem whose difficulties had made Léon Dufour recoil and whose solution seemed to me for a time undiscoverable. I tried, however, and had the satisfaction of succeeding, though not without some preliminary groping.
When flying from their caverns, intent upon the chase, the Cerceres would take any direction indifferently, turning now this way, now that; and they would come back, laden with their prey, from all quarters. Every part of the neighbourhood must therefore have been explored without distinction; but, as the huntresses were hardly more than ten minutes in coming and going, the radius worked could not be one of great extent, especially when we allow for the time necessary for the insect to discover its prey, to attack it and to reduce it to an inert mass. I therefore set myself to inspect the adjacent ground with every possible attention, in the hope of finding a few Cerceres engaged in hunting. An afternoon devoted to this thankless task ended by persuading me of [[34]]the futility of my quest and of the small chance which I had of catching in the act a few scarce huntresses, scattered here and there and soon lost to view through the swiftness of their flight, especially on difficult ground, thickly planted with vines and olive-trees. I abandoned the attempt.
By myself bringing live Weevils into the vicinity of the nests, might I not tempt the Cerceres with a victim all ready to hand and thus witness the desired tragedy? The idea seemed a good one; and the very next morning I went off in search of live specimens of Cleonus ophthalmicus. Vineyards, cornfields, lucerne-crops, hedges, stone-heaps, roadsides: I visited and inspected one and all; and, after two mortal days of minute investigation, I was the possessor—dare I say it?—I was the possessor of three Weevils, flayed, covered with dust, minus antennæ or tarsi, maimed veterans whom the Cerceres would perhaps refuse to look at! Many years have passed since the days of that fevered quest when, bathed in sweat, I made those wild expeditions, all for a Weevil; and, despite my almost daily entomological explorations, I am still ignorant how and where the celebrated Cleonus lives, though I meet him occasionally, roaming on the edge of the paths. O wonderful power of instinct! In the [[35]]selfsame places and in a mere fraction of time, our Wasps would have found by the hundred these insects undiscoverable by man; and they would have found them fresh and glossy, doubtless just issued from their nymphal cocoons!
No matter, let us see what we can do with my pitiful bag. A Cerceris has just entered her gallery with her usual prey; before she comes out again for a new expedition, I place a Weevil a few inches from the hole. The insect moves about; when it strays too far, I restore it to its position. At last the Cerceris shows her wide face and emerges from the hole; my heart beats with excitement. The Wasp stalks about the approaches to her home for a few moments, sees the Weevil, brushes against him, turns round, passes several times over his back and flies away without honouring my capture with a touch of her mandibles: the capture which I was at such pains to acquire. I am confounded, I am floored. Fresh attempts at other holes lead to fresh disappointments. Clearly these dainty sports-women will have none of the game which I offer them. Perhaps they find it uninteresting, not fresh enough. Perhaps, by taking it in my fingers, I have given it some odour which they dislike. With these epicures a mere alien touch is enough to produce disgust. [[36]]
Should I be more fortunate if I obliged the Cerceris to use her sting in self-defence? I enclosed a Cerceris and a Cleonus in the same bottle and stirred them up by shaking it. The Wasp, with her sensitive nature, was more impressed than the other prisoner, with his dull and clumsy organization; she thought of flight, not of attack. The very parts were interchanged: the Weevil, becoming the aggressor, at times seized with his snout a leg of his mortal enemy, who was so greatly overcome with fear that she did not even seek to defend herself. I was at the end of my resources; yet my wish to behold the catastrophe was but increased by the difficulties already experienced. Well, I would try again.
A bright idea flashed across my mind, entering so naturally into the very heart of the question that it brought hope in its train. Yes, that must be it; the thing was bound to succeed. I must offer my scorned game to the Cerceris in the heat of the chase. Then, carried away by her absorbing preoccupation, she would not perceive its imperfections.
I have already said that, on her return from hunting, the Cerceris alights at the foot of the slope, at some distance from the hole, whither she laboriously drags her prey. It became a matter, therefore, of robbing her of her victim [[37]]by drawing it away by one foot with my forceps and at once throwing her the live Weevil in exchange. The trick succeeded to perfection. As soon as the Cerceris felt her prey slip from under her belly and escape her, she tapped the ground impatiently with her feet, turned round and, perceiving the Weevil that had taken the place of her own, flung herself upon him and clasped him in her legs to carry him away. But she soon became aware that her prey was alive; and now the tragedy began, only to end with inconceivable rapidity. The Wasp faced her victim and, gripping its snout with her powerful mandibles, soon had it at her mercy. Then, while the Weevil reared on his six legs, the other pressed her forefeet violently on his back, as if to force open some ventral joint. I next saw the assassin’s abdomen slip under the Cleonus’ belly, bend into a curve, and dart its poisoned lancet briskly, two or three times, into the joint of the prothorax, between the first and second pair of legs. All was over in a moment. Without the least convulsive movement, without any of that stretching of the limbs which accompanies an animal’s death, the victim fell motionless for all time, as though struck by lightning. It was terribly and at the same time wonderfully quick. The murderess next turned the body on its back, [[38]]placed herself belly to belly with it, with her legs on either side, clasped it and flew away. Thrice over I renewed the experiment, with my three Weevils; and the process never varied.
Of course I gave the Cerceris back her first prey each time and withdrew my own Cleonus to examine him at my leisure. The inspection but confirmed my high opinion of the assassin’s formidable skill. It was impossible to perceive the least sign of a wound, the slightest flow of vital fluid at the point attacked. But what was most striking—and justly so—was the prompt and complete annihilation of all movement. Immediately after the murder I sought in vain for traces of irritability of the organs in the three Weevils dispatched before my eyes: those traces were never revealed, whether I pinched or pricked the insect; and it required the artificial means described above to provoke them. Thus these powerful Cleoni, which, if pierced alive with a pin and fixed on the insect-collector’s fatal sheet of cork, would have kicked and struggled for days and weeks, nay, for whole months on end, instantly lose all power of movement from the effect of a tiny prick which inoculates them with an invisible drop of venom. But chemistry has no poison so potent in so minute a dose; prussic acid would hardly produce those effects, if indeed it [[39]]can produce them at all. It is not to toxology then, surely, but to physiology and anatomy that we must turn to grasp the cause of this instantaneous annihilation; and to understand these marvellous happenings we must consider not so much the intense strength of the poison injected as the importance of the organ injured.
What is there, then, at the point where the sting enters? [[40]]
[1] ·528 oz. av.—Translator’s Note. [↑]
[2] ·88 oz. av.—Translator’s Note. [↑]
[3] For a description of this species, which is new to entomology, see the Appendix.—Author’s Note. [↑]
Chapter iii
A SCIENTIFIC SLAUGHTERER
The wasp has told us part of her secret by showing us the spot which her sting touches. Does this solve the question? Not yet, nor by a long way. Let us go back for a moment, forget what the insect has just taught us and, in our turn, set ourselves the problem of the Cerceris. The problem is this: to store underground, in a cell, a big enough pile of game to feed the larva which will be hatched from the egg laid on the heap.
At first sight this victualling seems simple enough; but a little reflection shows that it is attended by very grave difficulties. Our own game, for instance, is brought down by a shot from a gun; it is killed with horrible wounds. The Wasp has refinements of taste unknown to us: she must have the prey intact, with all its elegance of form and colouring, no broken limbs, no gaping wounds, no hideous disembowelling. Her victim has all the freshness of the live insect; it retains, without the loss of [[41]]a single speck, that fine tinted bloom which is destroyed by the mere contact of our fingers. If the insect were dead, if it were really a corpse, how great would be our difficulty in obtaining a like result! Each of us can kill an insect by brutally crushing it under foot; but to kill it neatly, with no sign of injury, is not an easy operation, is not an operation which any one can perform. How many would be utterly perplexed if they were called upon to kill, then and there, without crushing it, a hardy little insect which, even when you cut off its head, goes on struggling for a long time after! One has to be a practical entomologist to think of the various ways of asphyxiation; and even here success would be doubtful with primitive methods, such as the fumes of benzine or burning sulphur. In this unwholesome atmosphere the insect flounders about too long and loses its glory. We must have recourse to more heroic measures, such as the terrible exhalations of prussic acid emanating slowly from strips of paper steeped in cyanide of potassium, or else and better still, as being free from danger to the insect-hunter, the all-powerful fumes of bisulphide of carbon. It is quite an art, you see—and an art which has to call to its aid the formidable arsenal of chemistry—to kill an insect neatly, to do what the [[42]]Cerceris performs so quickly and so prettily, that is, if we are stupid enough to assume that her captured prey actually becomes a corpse.
A corpse! But that is by no means the fare prescribed for the larvæ, those little ogres clamouring for fresh meat, whom game ever so slightly high would inspire with insurmountable disgust. They want meat killed that day, with no suspicion of taint, the first sign of corruption. Nevertheless, the prey cannot be packed into the cell alive, as we pack the cattle destined to furnish fresh meat for the passengers and crew of a ship. What indeed would become of the delicate egg laid among live provisions? What would become of the feeble larva, a tiny grub which the least touch would bruise, among lusty Beetles who would go on kicking for weeks with their long, spurred legs? We need here two things which seem utterly irreconcilable: the immobility of death combined with the sweet wholesomeness of life. Before such a dietetic problem the most deeply read layman would stand powerless; the practical entomologist himself would own himself beaten. The Cerceris’ larder would defy their reasoning power.
Let us then suppose an academy of anatomists and physiologists; let us imagine a congress at which the question is raised among such men as [[43]]Flourens,[1] Magendie[2] and Claude Bernard.[3] If we want to obtain both complete immobility of the victim and also its preservation during a long period without going bad, the simplest and most natural idea which comes to us is that of tinned foods. Our congress would suggest the use of some preserving liquid, just as the famous Landes scientist did when he was confronted with his Buprestes; they would attribute exquisite antiseptic virtues to the Wasp’s poison-fluid; but these strange virtues would still remain to be proved. And perhaps the conclusion of that learned assembly, like the conclusion of the sage of the Landes, would be a purely gratuitous supposition which would simply substitute one unknown quantity for another, giving us in the place of the mystery of those uncorrupted tissues the mystery of that wonderful preserving fluid.
If we insist, if we point out that the larvæ need, not preserved food, which could never [[44]]possess the properties of still palpitating flesh, but something that shall be just as if it were live prey, despite its complete inertia, the learned congress, after due reflection, will fix on paralysis:
‘Yes, that’s it, of course! The creature must be paralysed; it must be deprived of movement, without being deprived of life.’
There is only one way of achieving this result: to injure, cut or destroy the insect’s nervous system in one or more skilfully-selected places. But, even at that stage, if left in hands unfamiliar with the anatomical secrets of a delicate organism, the question would not have advanced much further. What in fact is the disposition of this nervous system which has to be smitten if we would paralyse the insect without at the same time killing it? And, first of all, where is it? In the head, no doubt, and down the back, like the brain and the spinal marrow of the higher animals.
‘You make a grave mistake,’ our congress would say. ‘The insect is like an inverted animal, walking on its back; that is to say, instead of having the spinal marrow on the top, it has it below, along the breast and the belly. The operation on the insect to be paralysed must therefore be performed on the lower surface and on that surface alone.’ [[45]]
This difficulty once removed, another arises, equally serious in a different way. Armed with his scalpel, the anatomist can direct the point of his instrument wherever he thinks fit, in spite of obstacles, for these he can eliminate. The Wasp, on the contrary, has no choice. Her victim is a Beetle in his stout coat of mail; her lancet is her sting, an extremely delicate weapon which would inevitably be stopped by the horny armour. Only a few points are accessible to the fragile implement, namely, the joints, which are protected merely by an unresisting membrane. Moreover, the joints of the limbs, though vulnerable, do not in the least fulfil the desired conditions, for the utmost that could be obtained by means of them would be a partial paralysis and not a general paralysis affecting the whole of the motor organism. Without a prolonged struggle, which might be fatal to the patient, without repeated operations, which, if too numerous, might jeopardize the Beetle’s life, the Wasp has, if possible, to suppress all power of movement at one blow. It is essential, therefore, that she should aim her sting at the nervous centres, the seat of the motor faculties, whence radiate the nerves scattered over the several organs of movement. Now these sources of locomotion, these nervous centres, consist of a certain [[46]]number of nuclei or ganglia, more numerous in the larva, less numerous in the perfect insect and arranged along the median line of the lower surface in a string of beads more or less distant one from the other and connected by a double ribbon of the nerve-substance. In all the insects in the perfect state, the so-called thoracic ganglia, that is to say, those which supply nerves to the wings and legs and govern their movements, are three in number. These are the points to be struck. If their action can be destroyed, no matter how, the power of movement will be destroyed likewise.
There are two methods of reaching these motor centres with the Wasp’s feeble instrument, the sting: through the joint between the neck and the corselet; and through the joint between the corselet and the rest of the thorax, in short, between the first and second pair of legs. The way through the joint of the neck is hardly suitable: it is too far from the ganglia, which are near the base of the legs which they endow with movement. It is at the other point and there alone that the blow must be struck. That would be the opinion of the academy in which the Claude Bernards were treating the question in the light of their profound knowledge. And it is here, just here, between the first and second pair of legs, on [[47]]the median line of the lower surface, that the Wasp inserts her dirk. By what expert instinct is she inspired?
To select, as the spot wherein to drive her sting, the one vulnerable point, the point which none save a physiologist versed in insect anatomy could determine beforehand: even that is far from being enough. The Wasp has a much greater difficulty to surmount; and she surmounts it with an ease that stupefies us. The nerve-centres governing the locomotory organs of the insect are, we were saying, three in number. They are more or less distant from one another; sometimes, but rarely, they are close together. Altogether they possess a certain independence of action, so that an injury done to any one of them induces, at any rate for the moment, the paralysis only of the limbs that correspond with it, without affecting the other ganglia and the limbs which they control. To strike in succession these three motor centres, each farther back than the one before it, and to do so between the first and second pair of legs, seems an impracticable operation for such a weapon as the Wasp’s sting, which is too short and is besides very difficult to guide under such conditions. It is true that certain Beetles have the three ganglia of the thorax very near together, almost touching, [[48]]while others have the last two completely united, soldered, welded together. It is also a recognized fact that, in proportion as the different nervous nuclei tend towards a closer combination and greater centralization, the characteristic functions of animal nature become more perfect and consequently, alas, more vulnerable. Here we have the prey which the Cerceris really needs. Those Beetles with motor centres brought close together or even gathered into a common mass, making them mutually dependent on one another, will be at the same instant paralysed with a single stroke of the dagger; or, if several strokes be needed, the ganglia to be stung will at any rate all be there, collected under the point of the dart.
Which Beetles are they, then, that constitute a prey so eminently convenient for paralysing? That is the question. The lofty science of a Claude Bernard, concerning itself only with the fundamental generalities of organism and life, would not suffice here; it could never tell us how to make this entomological selection. I appeal to any physiologist under whose eyes these lines may come. Without referring to his library, could he name the Beetles in whom that centralization of the nervous system occurs; and, even with the aid of his books, would he at once know where to find the desired [[49]]information? The fact is that, with these minute details, we are now entering the domain of the specialist; we are leaving the public road for the path known to the few.
I find the necessary information in M. Émile Blanchard’s fine work on the nervous system of the Coleoptera.[4] I see there that this centralization of the nervous system is the prerogative, in the first place, of the Scarabæidæ, or Chafers; but most of these are too large: the Cerceris could perhaps neither attack them nor carry them away; besides, many of them live in the midst of ordure where the Wasp, herself so cleanly, would refuse to go in search of them. Motor centres very close together are found also in the Histers, who live on carrion and dung, in an atmosphere of loathsome smells, and who must therefore be eliminated; in the Scolyti, who are too small; and lastly in the Buprestes and the Weevils.
What an unexpected light amid the original darkness of the problem! Among the immense number of Beetles whereon the Cerceres might seem able to prey, only two groups, the Weevils and the Buprestes, fulfil the indispensable conditions. They live far removed from stench and filth, two qualities perhaps [[50]]invincibly repugnant to the dainty huntress; their numerous representatives vary considerably in size, in much the same way as their kidnappers, who can thus pick and choose the victims that suit them; they are far more vulnerable than any of the others at the one point where the Wasp’s dart can penetrate, for at this point the motor centres of the feet and wings are crowded together, all easily accessible to the sting. At this point, in the Weevils, the three thoracic ganglia are very close together, the last two even touching; at the same point, in the Buprestes, the second and third are mingled in one large mass, very near the first. And it is just Buprestes and Weevils that we see hunted, to the absolute exclusion of all other game, by the eight species of Cerceres whose provisions have been found to consist of Beetles! A certain inward resemblance, that is to say, the centralization of the nervous system, must therefore be the reason why the lairs of the different Cerceres are crammed with victims bearing no outward resemblance whatever.
The most exalted knowledge could make no more judicious choice than this, by which so great a collection of difficulties is magnificently solved that we wonder if we be not the dupes of some involuntary illusion, whether preconceived [[51]]theoretic notions have not obscured the actual facts, whether, in short, the pen have not described imaginary marvels. No scientific conclusion is firmly established until it has received confirmation by means of practical tests, carried out in every variety of way. We will therefore subject to experimental proof the physiological operation of which the Great Cerceris has just apprised us. If it be possible to obtain artificially what the Wasp obtains with her sting, namely, the abolition of movement and the continued preservation of the patient in a perfectly fresh condition; if it be possible to work this wonder with the Beetles hunted by the Cerceris, or with those presenting a similar nervous centralization, while we are unsuccessful with Beetles whose ganglia are far apart, then we shall be bound to admit, however hard to please we may be in the matter of tests, that in the unconscious inspiration of her instinct the Wasp has all the resources of consummate art. Let us see what experiment has to tell us.
The operating method is of the simplest. It is a question of taking a needle, or, better and more convenient, the point of a fine steel nib, and introducing a tiny drop of some corrosive fluid into the thoracic motor centres, by pricking the insect slightly at the junction of the [[52]]prothorax, behind the first pair of feet. The fluid which I employ is ammonia; but obviously any other liquid as powerful in its action would produce the same results. The nib being charged with ammonia as it might be with a very small drop of ink, I give the prick. The effects obtained differ enormously, according to whether we experiment upon species whose thoracic ganglia are close together or upon species in which those same ganglia are far apart. In the first class, my experiments were made on Dung-beetles: the Sacred Scarab[5] and the Wide-necked Scarab; on Buprestes: the Bronze Buprestis; lastly, on Weevils, in particular on the Cleonus hunted by the heroine of this essay. In the second class, I experimented on Ground-beetles: Carabi, Procrustes, Chlænii, Sphodri, Nebriæ; on Longicornes: Saperdæ and Lamiæ; on Melasoma-beetles: Cellar-beetles, Scauri, Asidæ.
In the Scarabæi, the Buprestes and the Weevils the effect is instantaneous: all movement ceases suddenly, without convulsions, so soon as the fatal drop has touched the nerve-centres. The Cerceris’ own sting produces no [[53]]more speedy annihilation. There is nothing more striking than this immediate immobility provoked in a powerful Sacred Beetle.
But this is not the only resemblance between the effects produced by the Wasp’s sting and those resulting from the nib poisoned with ammonia. The Scarabs, Buprestes and Beetles artificially stung, notwithstanding their complete immobility, preserve for three weeks, a month or even two the perfect flexibility of all their joints and the normal freshness of their internal organs. Evacuation takes place with them during the first days as in the normal state; and movements can be induced by the electric battery. In a word, they behave exactly like the Beetles immolated by the Cerceris; there is absolute identity between the state into which the kidnapper puts her victims and that which we produce at will by injuring the thoracic nerve-centres with ammonia. Now, as it is impossible to attribute the perfect preservation of the insect for so long a period to the tiny drop injected, we must reject altogether any notion of an antiseptic fluid and admit that, despite its perfect immobility, the insect is not really dead, that it still retains a glimmer of life, which for some time to come keeps the organs in their normal condition of freshness, but gradually fades out, until at last [[54]]it leaves them the prey of corruption. Besides, in some cases, the ammonia does not produce complete annihilation of movement except in the insect’s legs; and then, as the deleterious action of the liquid has doubtless not extended far enough, the antennæ preserve a remnant of mobility and we see the insect, even more than a month after the inoculation, draw them back quickly at the least touch: a convincing proof that life has not entirely deserted the inanimate body. This movement of the antennæ is also not uncommon in the Weevils wounded by the Cerceris.
In every case the injection of ammonia at once stops all movement in Scarabs, Weevils and Buprestes; but we do not always succeed in reducing the insect to the condition just described. If the wound be too deep, if the drop administered be too strong, the victim really dies; and, in two or three days’ time, we have nothing but a putrid body before us. If the prick, on the other hand, be too slight, the insect, after a longer or shorter period of deep torpor, comes to itself and at least partially recovers its power of motion. The assailant herself may sometimes operate clumsily, just like man, for I have noticed this sort of resurrection in a victim stung by the dart of a Digger-wasp. The Yellow-winged Sphex, whose [[55]]story will shortly occupy our attention, stacks her lairs with young Crickets first pricked with her poisoned lancet. I have extracted from one of those lairs three poor Crickets whose extreme limpness would, in any other circumstances, have denoted death. But here again death was only apparent. Placed in a flask, these Crickets kept in very good condition, perfectly motionless all the time, for nearly three weeks. In the end, two went mouldy, and the third partly revived, that is to say, he recovered the power of motion in his antennæ, in his mouth-parts and, what is more remarkable, in his first two pair of legs. If the Wasp’s skill sometimes fails to benumb the victim permanently, one can hardly expect invariable success from man’s rough experiments.
In the Beetles of the second class, that is to say, those whose thoracic ganglia are some distance apart, the effect of the ammonia is quite different. The least vulnerable are the Ground-beetles. A puncture which would have produced instant annihilation of movement in a large Sacred Beetle produces nothing but violent and disordered convulsions in the medium-sized Ground-beetles, be they Chlænius, Nebria or Calathus. Little by little the insect quiets down and, after a few hours’ rest, its usual movements are resumed as though it had [[56]]met with no accident whatever. If we repeat the experiment on the same specimen, twice, thrice, or four times over, the results remain the same, until the wound becomes too serious and the insect actually dies, as is proved by its desiccation and putrefaction, which follows soon after.
The Melasoma-beetles and Longicornes are more sensitive to the action of the ammonia. The injection of the corrosive drop pretty quickly renders them motionless; and, after a few convulsions, the insect seems dead. But this paralysis, which would have persisted in the Dung-beetles, the Weevils and the Buprestes, is only temporary here: within a day, motion is once more apparent, as energetic as ever. It is only when the dose of ammonia is of a certain strength that the movements fail to reappear; but then the insect is dead, quite dead, for it soon begins to decay. It is impossible, therefore, to produce complete and persistent paralysis in Beetles that have their ganglia far apart by the same measures which proved so efficacious in Beetles with ganglia close together: the utmost that we can obtain is a temporary paralysis whose effects pass off within a day.
The demonstration is conclusive; the Cerceres that prey on Beetles conform in their selection to what could be taught only by the [[57]]most learned physiologists and the finest anatomists. One would vainly strive to see no more in this than casual coincidences: it is not in chance that we shall find the key to such harmonies as these. [[58]]
[1] Marie Jean Pierre Flourens (1794–1867), the celebrated French physiologist, appointed perpetual secretary of the Academy of Science in 1833 and a member of the French Academy.—Translator’s Note. [↑]
[2] François Magendie (1783–1855), professor of anatomy in the Collège de France, noted for his experiments on the physiology of the nerves.—Translator’s Note. [↑]
[3] Claude Bernard (1813–1878), another distinguished French physiologist and perhaps the most famous representative of experimental science in the nineteenth century.—Translator’s Note. [↑]
[4] Annales des sciences naturelles, Series III., vol. v.—Author’s Note. [↑]
[5] For the Sacred Scarab, or Sacred Beetle, cf. Insect Life, by J. H. Fabre, translated by the author of Mademoiselle Mori: chaps. i. and ii.; and The Life and Love of the Insect, by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chaps, i. to iv.—Translator’s Note. [↑]
Chapter iv
THE YELLOW-WINGED SPHEX
Under their powerful armour, which no dart can penetrate, the insects of the Beetle tribe offer but a single vulnerable spot to the sting-bearing enemy. This defect in the breastplate is known to the murderess, who drives in her poisoned dagger there and at one blow strikes the three motor centres, for she selects her victims from the Weevil and Buprestis families, whose nervous system is centralized to the requisite degree. But what will happen when the prey is an insect clad not in mail but in a soft skin, which the Wasp can stab here or there indifferently, in any part of the body that chances to be exposed? In that case are the blows still delivered scientifically? Like the assassin who strikes at the heart to cut short the dangerous resistance of his victim, does the assailant follow the tactics of the Cerceres and wound the motor ganglia by preference? If that be so, then what happens when these ganglia are some distance apart and so independent [[59]]in their action that paralysis of one is not necessarily followed by paralysis of the others? These questions will be answered by the story of a Cricket-huntress, the Yellow-winged Sphex (Sphex flavipennis).
It is at the end of July that the Yellow-winged Sphex tears the cocoon that has protected her until then and flies out of her subterranean cradle. During the whole of August she is frequently seen flitting, in search of some drop of honey, around the spiked heads of the field eryngo, the commonest of the hardy plants that brave the heat of the dog-days in this month. But this careless life does not last long, for by the beginning of September the Sphex is at her arduous task as a sapper and huntress. She generally selects some small plateau, on the high banks by the side of the roads, wherein to establish her home, provided that she find two indispensable things there: a sandy soil, easy to dig; and sunshine. No other precaution is taken to protect the dwelling against the autumn rains or winter frosts. A horizontal site, unprotected, lashed by the rain and the winds, suits her perfectly, on condition, however, that it is exposed to the sun. And, when a heavy shower comes in the middle of her mining, it is pitiful next day to see the half-built galleries in ruins, choked [[60]]with sand and finally abandoned by their engineers.
The Sphex seldom practises her industry alone; the site selected is usually exploited by small bands of ten or twenty sappers or more. One must have spent days in contemplating one of these villages to form any idea of the restless activity, the spasmodic haste, the abrupt movements of those hard-working miners. The soil is rapidly attacked with the rakes of the forefeet: canis instar, as Linnæus says. No mischievous puppy displays more energy in digging up the ground. At the same time, each worker sings her glad ditty, which consists of a shrill and strident noise, constantly broken off and modulated by the vibrations of the wings and thorax. One would think that they were a troop of merry companions encouraging one another in their work with a cadenced rhythm. Meanwhile the sand flies, falling in a fine dust on their quivering wings; and the too bulky gravel, removed bit by bit, rolls far away from the workyard. If a piece seems too heavy to be moved, the insect gets up steam with a shrill note which reminds one of the woodman’s ‘Hoo!’ Under the redoubled efforts of tarsi and mandibles the cave soon takes shape; the insect is already able to dive into it bodily. We then see a lively alternation of forward [[61]]movements, to loosen new materials, and backward movements, to sweep the rubbish outside. In this constant hurrying to and fro the Sphex does not walk, she darts as though shot from a spring; she bounds with throbbing abdomen and quivering antennæ, her whole body, in short, animated with a musical vibration. The miner is now out of sight; but we still hear underground her untiring song, while at intervals we catch a glimpse of her hind-legs, pushing a torrent of sand backwards to the mouth of the burrow. From time to time the Sphex interrupts her subterranean labours, either to come and dust herself in the sun, to rid herself of the grains of sand which, slipping into her delicate joints, might hamper the liberty of her movements, or else to reconnoitre the neighbourhood. Despite these interruptions, which for that matter do not last long, the gallery is dug in the space of a few hours; and the Sphex comes to her threshold to chant her triumph and give the finishing polish to her work by removing some unevenness and carrying away a speck or two of earth whose drawbacks are perceptible to her discerning eye alone.
Of the numerous tribes of Sphex-wasps which I have visited, one in particular remains fixed in my memory because of its curious dwelling-place. [[62]]On the edge of a high-road were some small heaps of mud, taken from the ditches by the road-mender’s shovel. One of these heaps, long ago dried in the sun, formed a cone-shaped mound, resembling a large sugar-loaf twenty inches high. The site seemed to have attracted the Wasps, who had established themselves there in a more populous colony than I have ever since beheld. The cone of dry mud was riddled from top to bottom with burrows, which gave it the appearance of an enormous sponge. On every storey there was a feverish animation, a busy coming and going which reminded one of the scenes in some great yard when the work is urgent. Crickets were being dragged by the antennæ up the slopes of the conical city; victuals were being stored in the larders of the cells; dust was pouring from the galleries in process of excavation by the miners; grimy faces appeared at intervals at the mouths of the tunnels; there were constant exits and constant entrances; and now and again a Sphex, in her brief intervals of leisure, would climb to the top of the cone, perhaps to cast a look of satisfaction from this belvedere over the works in general. What a spectacle to tempt me, to make me long to carry the whole city and its inhabitants away with me! It was useless even to try: the mass was too [[63]]heavy. One cannot root up a village from its foundations to transplant it elsewhere.
We will return, therefore, to the Sphex-wasps working on level ground, in ordinary soil, as happens in by far the greater number of cases. As soon as the burrow is dug, the chase begins. Let us profit by the Wasp’s distant excursions in search of her game and examine the dwelling. The usual site of a Sphex colony is, as I said, level ground. Nevertheless, the soil is not so smooth but that we find a few little mounds crowned with a tuft of grass or wormwood, a few cracks consolidated by the scanty roots of the vegetation that covers them. It is in the sides of these furrows that the Sphex builds her dwelling. The gallery consists first of a horizontal portion, two or three inches long and serving as an approach to the hidden retreat destined for the provisions and the larvæ. It is in this entrance-passage that the Sphex takes shelter in bad weather; it is here that she retires for the night and rests for a few moments in the daytime, putting outside only her expressive face, with its great, bold eyes. Following on the vestibule comes a sudden bend, which descends more or less obliquely to a depth of two or three inches more and ends in an oval cell of somewhat larger diameter, whose main axis lies horizontally. The walls [[64]]of the cell are not coated with any particular cement; but, in spite of their bareness, we can see that they have been the object of the most conscientious labour. The sand has been heaped up and carefully levelled on the floor, the ceiling and the sides, so as to prevent landslips and remove any roughness that might hurt the delicate skin of the grub. Lastly, this cell communicates with the passage by a narrow entrance, just wide enough to admit the Sphex laden with her prey.
When this first cell is supplied with an egg and the necessary provisions, the Sphex walls up the entrance, but does not yet abandon her burrow. A second cell is dug beside the first and victualled in the same way; then a third and sometimes a fourth. Not till then does the Sphex shoot back into the burrow all the rubbish accumulated outside the door and completely remove all the outward traces of her work. Thus, to each burrow there are usually three cells, rarely two and still more rarely four. Now, as we ascertain when dissecting the insect, we can estimate the number of eggs laid at about thirty, which brings up to ten the number of burrows needed. On the other hand, the operations are hardly begun before September and are finished by the end of the month. The Sphex, therefore, can devote [[65]]only two or three days at most to each burrow and its provisioning. No one will deny that the active little creature has not a moment to lose, when, in so short a time, she has to excavate her den, to procure a dozen Crickets, to carry them sometimes from a distance in the face of innumerable difficulties, to store them away and finally to stop up the burrow. And, besides, there are days when the wind makes hunting impossible, rainy days or even merely grey days, which cause all work to be suspended. One can readily imagine from this that the Sphex is unable to give to her buildings the perhaps permanent solidity which the Great Cerceres bestow upon their long galleries. The latter hand down from generation to generation their substantial dwellings, each year excavated to a greater depth than the last, galleries which threw me into a sweat when I tried to inspect them and which generally triumphed over my efforts and my implements. The Sphex does not inherit the work of her predecessors: she has to do everything for herself and quickly. Her dwelling is but a tent, hastily pitched for a day and shifted on the morrow. As compensation, the larvæ, who have only a thin layer of sand to cover them, are capable themselves of providing the shelter which their mother could not create: they [[66]]clothe themselves in a threefold and fourfold waterproof wrapper, far superior to the thin cocoon of the Cerceres.
But here, with a loud buzz, comes a Sphex who, returning from the chase, stops on a neighbouring bush, holding in her mandibles, by one antenna, a large Cricket, several times her own weight. Exhausted by the burden, she takes a moment’s rest. Then she once more grips her captive between her feet and, with a supreme effort, covers in one flight the width of the ravine that separates her from her home. She alights heavily on the level ground where I am watching, in the very middle of a Sphex village. The rest of the journey is performed on foot. The Wasp, not at all intimidated by my presence, bestrides her victim and advances, bearing her head proudly aloft and hauling the Cricket, who trails between her legs, by an antenna held in her mandibles. If the ground be bare, it is easy to drag the victim along; but, should some grass-tuft spread the network of its shoots across the road, it is curious to observe the amazement of the Sphex when one of these little ropes suddenly thwarts her efforts; it is curious to witness her marches and counter-marches, her reiterated attempts, until the obstacle is overcome, either with the aid of the [[67]]wings or by means of a clever deviation. The Cricket is at last conveyed to his destination and is so placed that his antennæ exactly touch the mouth of the burrow. The Sphex then abandons her prey and descends hurriedly to the bottom of the cave. A few seconds later we see her reappear, showing her head out of doors and giving a little cry of delight. The Cricket’s antennæ are within her reach; she seizes them and the game is brought quickly down to the lair.
I still ask myself, without being able to find a sufficiently convincing solution, the reason for these complicated proceedings at the moment when the Cricket is introduced into the burrow. Instead of going down to her den alone, to reappear afterwards and pick up the prey left for a time on the threshold, would not the Sphex have done better to continue to drag the Cricket along the gallery as she does in the open air, seeing that the width of the tunnel permits it, or else to go in first, backwards, and pull him after her? The various Predatory Wasps whom I have hitherto been able to observe carry down to their cells straight away, without preliminaries, the game which they hold clasped beneath their bellies with the aid of their mandibles and their middle-legs. Léon Dufour’s Cerceris begins by complicating her procedure, [[68]]because, after laying her Buprestis for a moment at the door of her underground home, she at once enters her gallery backwards and then seizes the victim with her mandibles and drags it to the bottom of the burrow. But it is a far cry from these tactics and those adopted in a like case by the Cricket-hunters. Why that domiciliary visit which invariably precedes the entrance of the game? Could it not be that, before descending with a cumbrous burden, the Sphex thinks it wise to take a look at the bottom of her dwelling, so as to make sure that all is well and, if necessary, to drive out some brazen parasite who may have slipped in during her absence? If so, who is the parasite? Several Diptera, Predatory Gnats, especially Tachinæ, watch at the doors of the Hunting Wasps, spying for the propitious moment to lay their eggs on others’ provisions; but none of them enters the home or ventures into the dark passages where the owner, if by ill-luck she happened to be in, would perhaps make them pay dearly for their audacity. The Sphex, like all the rest, pays her tribute to the plundering Tachinæ; but these never enter the burrow to perpetrate their misdeeds. Besides, have they not all the time that they need to lay their eggs on the Cricket? If they are sharp about it, they can easily profit by the [[69]]temporary abandonment of the victim to entrust their progeny to it. Some greater danger still must therefore threaten the Sphex, since her preliminary descent of the burrow is of such imperious necessity.
Here is the only fact observed by myself that may throw a little light on the problem. Amid a colony of Sphex-wasps in full swing, a colony from which any other Wasp is usually excluded, I one day surprised a huntress of a different genus, Tachytes nigra, carrying one by one, without hurrying, in the midst of the crowd where she was but an intruder, grains of sand, bits of little dry stalks and other diminutive materials to stop up a burrow of the same shape and width as the adjacent burrows of the Sphex. The labour was too carefully performed to allow of any doubt of the presence of the worker’s egg in the tunnel. A Sphex moving about uneasily, apparently the lawful owner of the burrow, did not fail, each time that the strange Wasp entered the gallery, to rush in pursuit of her; but she emerged swiftly, as though frightened, followed by the other, who impassively continued her work. I inspected this burrow, evidently an object in dispute between the two Wasps, and found in it a cell provisioned with four Crickets. Suspicion almost makes way for certainty: these provisions [[70]]are far in excess of the needs of a Tachytes-grub, who is certainly not more than half the size of the larva of the Sphex. She whose impassiveness, whose care to stop up the burrow would at first have made one take her for the mistress of the house, was in reality a mere usurper. How is it that the Sphex, who is larger and more powerful than her adversary, allows herself to be robbed with impunity, confining herself to fruitless pursuits and fleeing like a coward when the interloper, who does not even appear to notice her presence, turns round to leave the burrow? Can it be that, in insects as in man, the first chance of success lies in de l’audace, encore de l’audace et toujours de l’audace? The usurper certainly had audacity and to spare. I see her still, with imperturbable calmness, moving in and out in front of the complaisant Sphex, who stamps her feet with impatience but does not fall upon the thief.
I will add that, in other circumstances, I have repeatedly found the same Wasp, whom I presume to be a parasite, in short the Black Tachytes, dragging a Cricket by one of his antennæ. Was he a lawfully-acquired prey? I should like to think so; but the vacillating behaviour of the insect, who went straying about the ruts in the roads as though seeking for a [[71]]burrow to suit it, always left me uncertain. I have never witnessed its digging-work, if it really undertakes the labour of excavation. And, a more serious matter, I have seen it leave its game on the rubbish-heap, perhaps not knowing what to do with it, for lack of a burrow wherein to place it. Such wastefulness as this seems to me to point to ill-gotten goods; and I ask myself if the Cricket were not stolen from the Sphex at the moment when she abandoned her prey on the threshold. My suspicions also fall upon Tachytes obsoleta, banded with white round the abdomen like Sphex albisecta and feeding her larvæ on Crickets similar to those hunted by the latter. I have never seen her digging any galleries, but I have caught her with a Cricket whom the Sphex would not have rejected. This identity of provisions in species of different genera raises doubts in my mind as to the lawfulness of the booty. Let me add, lastly, to atone in a measure for the injury which my suspicions may do to the reputation of the genus, that I have been the eye-witness of a perfectly straightforward capture of a small and still wingless Cricket by Tachytes tarsina and that I have seen her digging cells and victualling them with game acquired by her own valiant exertions.
I have therefore only suspicions to offer in [[72]]explanation of the obstinacy of the Sphex-wasps in going down their tunnels before carrying in their prey. Can they have some other object besides that of dislodging a parasite who may have arrived during their absence? This is what I despair of ever knowing; for who can interpret the thousand ruses of instinct? Poor human reason, which cannot even fathom the wisdom of a Sphex!
At any rate, it has been proved that these ruses are singularly invariable. In this connection I will mention an experiment which interested me greatly. Here are the particulars: at the moment when the Sphex is making her domiciliary visit, I take the Cricket left at the entrance to the dwelling and place her a few inches farther away. The Sphex comes up, utters her usual cry, looks here and there in astonishment, and, seeing the game too far off, comes out of her hole to seize it and bring it back to its right place. Having done this, she goes down again, but alone. I play the same trick upon her; and the Sphex has the same disappointment on her arrival at the entrance. The victim is once more dragged back to the edge of the hole, but the Wasp always goes down alone; and this goes on as long as my patience is not exhausted. Time after time, forty times over, did I repeat the [[73]]same experiment on the same Wasp; her persistency vanquished mine and her tactics never varied.
Having demonstrated the same inflexible obstinacy which I have just described in the case of all the Sphex-wasps on whom I cared to experiment in the same colony, I continued to worry my head over it for some time. What I asked myself was this:
‘Does the insect obey a fatal tendency, which no circumstances can ever modify? Are its actions all performed by rule; and has it no power of acquiring the least experience on its own account?’
Some additional observations modified this too absolute view. Next year I visit the same spot at the proper season. The new generation has inherited the burrowing-site selected by the previous generation; it has also faithfully inherited its tactics: the experiment of withdrawing the Cricket yields the same results. Such as last year’s Sphex-wasps were, such are those of the present year, equally persistent in a fruitless procedure. The illusion was simply growing worse, when good fortune brought me into the presence of another colony of Sphex-wasps, in a district at some distance from the first. I recommenced my attempts. After two or three experiments with results similar to [[74]]those which I had so often obtained, the Sphex got astride of the Cricket, seized him with her mandibles by the antennæ, and at once dragged him into the burrow. Who was the fool now? Why, the experimenter foiled by the clever Wasp! At the other holes, her neighbours likewise, one sooner, another later, discovered my treachery and entered the dwelling with the game, instead of persisting in abandoning it on the threshold to seize it afterwards. What did all this mean? The colony which I was now inspecting, descended from another stock—for the children return to the site selected by their parents—was cleverer than the colony of the year before. Craft is handed down: there are tribes that are sharper-witted and tribes that are duller-witted, apparently according to the faculties of their elders. With the Sphex as with us, the intellect differs with the province.
Next day, in a different locality, I repeated my experiment with another Cricket; and every time the Sphex was hoodwinked. I had come upon a dense-minded tribe, a regular village of Bœotians, as in my first observations. [[75]]
Chapter v
THE THREE DAGGER-THRUSTS
There is no doubt that the Sphex displays her most cunning resources at the moment of immolating a Cricket; it is important, therefore, to ascertain the manner wherein the victim is sacrificed. Profiting by the repeated attempts which I had made when I was studying the tactics of the Cerceres, I at once applied to the Sphex the method which had succeeded with the other Wasps, a method that consisted in taking the prey from the huntress and forthwith replacing it by another, living prey. The substitution is all the easier inasmuch as we have seen the Sphex herself releasing her victim in order to go down the burrow for a moment alone. Her daring familiarity, which makes her come and take from your fingers and even out of your hand the Cricket whom you have stolen from her and now offer her again, also lends itself admirably to the successful issue of the experiment, by allowing you to observe every detail of the drama closely. [[76]]
Again, to find live Crickets is an easy matter: we have but to lift the first stone that we see and we find them crouching underneath, sheltered from the sun. These Crickets are young ones, of the same year, who as yet boast but rudimentary wings and who, not possessing the industry of the full-grown insect, have not learnt to dig those cavernous retreats where they would be safe from the Sphex’ investigations. In a few moments I have as many live Crickets as I could wish for. This completes my preparations. I climb to the top of my observatory, establish myself on the level ground, in the centre of the Sphex village, and wait.
A huntress appears upon the scene, carts her Cricket to the entrance of the home and goes down her burrow by herself. I quickly remove the Cricket and substitute one of mine, placing him, however, some distance away from the hole. The kidnapper returns, looks round, and runs and seizes the victim, which is too far off for her. I am all eyes, all attention. Nothing would induce me to give up my part in the tragic spectacle which I am about to witness. The terrified Cricket takes to flight, hopping as fast as he can; the Sphex pursues him hot-foot, reaches him, rushes upon him. There follows, amid the dust, a confused encounter, wherein each champion, now victor, now vanquished, by [[77]]turns is at the top or at the bottom. Success, for a moment undecided, at last crowns the aggressor’s efforts. Despite his vigorous kicks, despite the snaps of his pincer-like mandibles, the Cricket is laid low and stretched upon his back.
The murderess soon makes her arrangements. She places herself belly to belly with her adversary, but in the opposite direction, grasps one of the threads at the tip of the Cricket’s abdomen with her mandibles and masters with her fore-legs the convulsive efforts of his thick hinder thighs. At the same time, her middle-legs hug the heaving sides of the beaten insect; and her hind-legs, pressing like two levers on the front of the head, force the joint of the neck to open wide. The Sphex then curves her abdomen vertically, so as to offer only an unattackable convex surface to the Cricket’s mandibles; and we see, not without emotion, its poisoned lancet drive once into the victim’s neck, next into the joint of the front two segments of the thorax, and lastly towards the abdomen. In less time than it takes to relate, the murder is consummated; and the Sphex, after adjusting the disorder of her toilet, makes ready to haul home the victim, whose limbs are still quivering in the throes of death.
Let us consider for a moment the excellence [[78]]of the tactics of which I have given a feeble glimpse. The Cerceris attacks a passive adversary, incapable of flight, almost devoid of offensive weapons, whose sole chances of safety lie in a stout cuirass, the weak point of which, however, is known to the murderess. But what a difference here! The quarry is armed with dreadful mandibles, capable of disembowelling the assailant if they succeed in seizing her; it sports a pair of powerful legs, regular clubs bristling with a double row of sharp spikes, which can be used either to enable the Cricket to hop out of his enemy’s reach, or to send her sprawling with brutal kicks. Observe, therefore, the precautions which the Sphex takes before setting her sting in motion. The victim, turned upon his back, cannot, for lack of any purchase, use his hind-levers to escape with, which he certainly would do if he were attacked in the normal position, as are the big Weevils of the Great Cerceris. His spurred legs, mastered by the Sphex’ fore-feet, cannot act as offensive weapons either; and his mandibles, kept at a distance by the Wasp’s hind-legs, open in wide menace without being able to seize a thing. But it is not enough for the Sphex to render her Cricket incapable of hurting her; she must also hold him so firmly pinioned that he cannot make the slightest [[79]]movement capable of diverting the sting from the points at which the poison is to be injected; and it is probably with the object of stilling the movements of the abdomen that one of its terminal threads is grasped. No, if a fertile imagination had allowed itself free scope to invent a plan of attack at will, it could not have contrived anything better; and it is open to doubt whether the athletes of the classic palestræ, when grappling with an adversary, boasted more scientific attitudes.
I have said that the sting is driven several times into the patient’s body: first under the neck, then behind the prothorax, next and lastly towards the top of the abdomen. It is in these three dagger-thrusts that the infallibility and the intuitive science of instinct appear in all their splendour. Let us first recall the principal conclusions to which our earlier study of the Cerceris has led us. The victims of the Wasps whose larvæ live on prey are not proper corpses, in spite of their immobility, which is sometimes complete. They suffer simply from a total or partial locomotory paralysis, from a more or less thorough annihilation of animal life; but vegetable life, the life of the organs of nutrition, is maintained for a long while yet and preserves from decomposition the prey which the larva is not to devour [[80]]for some time to come. To produce this paralysis the Hunting Wasps employ precisely the process which the advanced science of our own day might suggest to the experimental physiologists, that is to say, they injure, by means of their poisoned sting, the nerve-centres that control the locomotory organs. We know besides that the several centres or ganglia of the nervous system of articulate animals are, within certain limits, independent of one another in their action, so that an injury to any one of them does not, or at any rate not immediately, entail more than the paralysis of the corresponding segment; and this applies all the more when the different ganglia are farther apart. When, on the other hand, they are welded together, the lesion of this common centre induces paralysis of all the segments over which its ramifications are distributed. This is the case with the Buprestes and the Weevils, whom the Cerceres paralyse with a single thrust of the sting, aimed at the common mass of the nerve-centres of the thorax. But open a Cricket. What do we find to set the three pairs of legs in motion? We find what the Sphex knew long before the anatomists: three nerve-centres at a great distance one from the other. Hence the magnificent logic of her needle-thrusts thrice repeated. Proud science, bend the knee! [[81]]
Despite the appearances that might make us think otherwise, the Crickets immolated by the Yellow-winged Sphex are no more dead than the Weevils pierced by the Cerceris’ dart. The flexibility of the victims’ integuments, faithfully revealing the slightest internal movement, enables us in this case to dispense with the artificial methods which I employed to demonstrate the presence of a remnant of life in the Cleoni of the Great Cerceris. In fact, if we assiduously observe a Cricket stretched on his back, a week, a fortnight even or more after the murder, we see the abdomen heaving deeply at long intervals. Pretty often we can still perceive a few quiverings in the palpi and exceedingly-pronounced movements on the part of both the antennæ and the abdominal threads, which diverge and separate and then suddenly come together. I have succeeded, by placing the sacrificed Crickets in glass tubes, in keeping them perfectly fresh for a month and a half. Consequently, the Sphex-grubs, which live for less than a fortnight before shrouding themselves in their cocoons, are certain of fresh meat until their banquet is finished.
The chase is over; the three or four Crickets that are the allotted portion of each cell are stacked methodically, lying on their backs, with their heads at the far end of the cell and their [[82]]feet at the entrance. An egg is laid on one of them. The burrow must now be closed. The sand resulting from the excavation, which is lying in a heap outside the front-door, is quickly swept backwards down the passage. From time to time some fair-sized bits of gravel are picked out singly, by scratching the heap of rubbish with the fore-feet, and carried with the mandibles to strengthen the crumbly mass. Should the Wasp find none within reach to suit her, she goes and searches for them in the neighbourhood, and seems to choose them as conscientiously as a mason would choose the chief stones for his building. Vegetable remains, tiny fragments of dead leaves, are also employed. In a few moments every outward trace of the underground dwelling has disappeared; and, if we have not been careful to mark the site of the abode, it becomes impossible for the most watchful eye to find it again. When this is finished, a new burrow is dug, provisioned and walled up as often as the teeming ovaries demand. Having completed the laying of her eggs, the Sphex resumes her careless, vagrant life, until the first cold snap puts an end to her well-filled existence.
The Sphex’ task is accomplished; and I will finish mine with an examination of her weapon. The organ destined for the elaboration of her [[83]]poison consists of two prettily-ramified tubes, ending separately in a common reservoir or phial, shaped like a pea. From this phial starts a slender channel which runs down the axis of the sting and conducts the little drop of poison to its tip. The dimensions of the lancet are very small and not such as one would expect from the size of the Sphex, and especially from the effects which its prick produces on the Crickets. The point is quite smooth and entirely deprived of those backward indentations which we find in the Hive-bee’s sting. The reason for this is obvious. The Bee uses her sting only to avenge an injury, even at the cost of her life; and the teeth of the dart resist its withdrawal from the wound and thus cause mortal ruptures in the viscera at the extremity of the abdomen. What would the Sphex have done with a weapon that would have been fatal to her on her first expedition? Supposing that the dart could be withdrawn in spite of its teeth, I doubt whether any Hymenopteron using her weapon chiefly to wound the game destined for her larvæ would be supplied with a toothed sting. With her, the dirk is not a show weapon, unsheathed to satisfy revenge: revenge, the so-called pleasure of the gods, but a very costly pleasure, for the vindictive Bee sometimes pays for it with her life; it is an implement for use, [[84]]a tool, on which the future of the grubs depends. It must therefore be one easy to wield in the struggle with the captured prey; it must be capable of being inserted in the flesh and withdrawn without the least hesitation, a condition much better fulfilled by a smooth than by a barbed blade.
I wished to find out at my own expense if the Sphex’ sting is very painful, this sting which lays low sturdy victims with terrible rapidity. Well, I confess with profound admiration that it is insignificant and bears no comparison, for intensity of pain, with the stings of the irascible Bees and Social Wasps. It hurts so little that, instead of using the forceps, I would not scruple to take in my fingers any live Sphex-wasps that I needed in my experiments. I can say the same of the different Cerceres, of the Philanthi,[1] of the Palari, of even the huge Scoliæ,[2] whose very view inspires dismay, and, generally speaking, of all the Hunting Wasps that I have been able to observe. I make an exception of the Spider-huntresses, the Pompili;[3] and even [[85]]then their sting is much less painful than the Bees’.
One last word: we know how furiously the Hymenoptera armed with a purely defensive dart—the Social Wasps, for instance—rush upon him who is bold enough to disturb their dwelling-house and punish him for his temerity. On the other hand, those whose sting is intended for killing game are very pacific, as though they were aware of the importance which the little drop of poison in their phial possesses for their family. This tiny drop is the safeguard of their race, I might say, its livelihood; and so they are very economical in its use, reserving it for the serious business of the chase, without any parade of vindictive courage. I was not once punished with a sting when I established myself amid the villages of our various Hunting Wasps, though I overturned their nests and stole the larvæ and the provisions. You must lay hold of the insect to make it use its weapon; and even then it does not always pierce the skin, unless you place within its reach a part more delicate than the fingers, such as, for instance, the wrist. [[86]]
[1] For Philanthus Apivorus, the Bee-eating Wasp, cf. Social Life in the Insect World, by J. H. Fabre, translated by Bernard Miall: chap. xiii.—Translator’s Note. [↑]
[2] Cf. The Life and Love of the Insect: chap. xi.—Translator’s Note. [↑]
[3] Cf. The Life and Love of the Insect: chap. xii.—Translators Note. [↑]
Chapter vi
THE LARVA AND THE NYMPH
The egg of the Yellow-winged Sphex is white, elongated, cylindrical, slightly bow-shaped and measures three to four millimetres[1] in length. So far from being laid anywhere on the victim, at random, it is deposited on a specially favoured spot, which is always the same; in short, it is placed across the Cricket’s breast, a little to one side, between the first and second pair of legs. The egg of the White-edged Sphex and that of the Languedocian Sphex occupy a similar position: the first on the breast of a Locust, the second on the breast of an Ephippiger.[2] The point selected must present some peculiarity of great importance to the young larva’s safety, for I have never known it to vary.
The egg hatches after three or four days. A very delicate wrapper tears asunder; and there lies before our eyes a feeble grub, transparent as crystal, a little attenuated and as it [[87]]were compressed in front, slightly swollen at the back and adorned on either side with a narrow white thread formed of the principal trachean ducts. The frail creature occupies the same position as the egg. Its head is, so to speak, planted at the very spot where the upper end of the egg was fixed; and all the remainder simply rests upon the victim, without being fastened to it. The grub’s transparency enables us readily to distinguish rapid undulations inside it, ripples which follow one upon the other with mathematical regularity and which, beginning in the middle of the body, spread some forward and some backward. These fluctuating movements are due to the digestive canal, which takes long draughts of the juices drawn from the victim’s body.
Let us dwell for a moment upon a sight which cannot fail to attract our attention. The Wasp’s prey lies on its back, motionless. In the cell of the Yellow-winged Sphex it is a Cricket, or rather three or four Crickets stacked one atop the other; in the cell of the Languedocian Sphex it is a single head of game, but large in proportion, a fat-bellied Ephippiger. The grub is lost should it happen to be torn from the spot whence it derives life; a fall would be the end of it, for, weak as it is and deprived of all means of motion, how could it [[88]]make its way back to the spot at which it slakes its appetite? The slightest movement would enable the victim to rid itself of the atom gnawing at its entrails; and yet the gigantic prey submits meekly, without the least quiver of protest. I well know that it is paralysed, that it has lost the use of its legs through the sting of its murderess; but still, recent victim that it is, it retains more or less power of movement and sensation in the regions not affected by the dart. The abdomen throbs, the mandibles open and close, the abdominal filaments wave to and fro, as do the antennæ. What would happen if the worm were to bite into one of the still impressionable parts, near the mandibles, or even on the belly, which, being more tender and more succulent, seems as though it ought, after all, to supply the first mouthfuls of the feeble grub? Bitten to the quick, the Cricket, Locust or Ephippiger would at least shiver; and this faint tremor of the skin would be enough to shake off the tiny larva and bring it to the ground, where it would no doubt perish, for it might at any moment find itself in the grips of those dreadful mandibles.
But there is one part of the body where no such danger is to be feared, the part which the Wasp has wounded with her sting—in short, [[89]]the thorax. Here and here alone, on a victim of recent date, the experimenter can rummage with a needle, driving it through and through, without producing a sign of suffering in the patient. Well, it is here that the egg is invariably laid; it is here that the young larva always takes its first bite at its prey. Gnawed at a point no longer susceptible to pain, the Cricket remains motionless. Later, when the wound has reached a sensitive point, he will doubtless toss about to such extent as he can; but then it will be too late: his torpor will be too deep; and besides the enemy will have gained strength. This explains why the egg is laid on a spot which never varies, near the wounds caused by the sting—in short, on the thorax: not in the middle, where the skin would perhaps be too thick for the new-born grub, but on one side, towards the juncture of the legs, where it is much thinner. What a judicious choice, how logical on the part of the mother when, underground, in complete darkness, she discerns the one suitable spot on the victim and selects it for her egg!
I have reared Sphex-grubs by giving them, one after the other, the Crickets taken from the cells; and I was then able to follow day by day the rapid progress of my nurselings. The first Cricket, the one on whom the egg was [[90]]laid, is attacked, as I have said, near the point where the huntress administered her second sting, that is to say, between the first and second pair of legs. In a few days the young larva has dug in the victim’s breast a hollow large enough to admit half its body. It is not uncommon to see the Cricket, bitten to the quick, uselessly waving his antennæ and his abdominal threads, opening and closing his mandibles on space and even moving a leg. But the enemy is safe and is ransacking his entrails with impunity. What an awful nightmare for the paralysed Cricket!
The first ration is finished in six or seven days’ time; none of it remains but the framework of skin, with all its parts more or less in position. The larva, whose length is now twelve millimetres,[3] leaves the Cricket’s body through the hole in the thorax which it made to start with. During this operation it moults; and its cast skin often remains caught in the opening through which it made its exit. It rests after the moulting and then attacks a second ration. Being stronger now, the larva has nothing to fear from the feeble movements of the Cricket, whose daily-increasing torpor has had time to extinguish the last glimmers of resisting-power during the week and more [[91]]that has elapsed since the dagger-thrusts were given. It is therefore assailed with no precautions, usually at the belly, which is the tenderest part and the richest in juices. Soon the turn comes of the third Cricket and lastly of the fourth, who is devoured in ten hours or so. Of these last three victims all that remains is the tough integuments, whose various parts are severed one by one and carefully emptied. If a fifth ration be presented, the larva scorns it, or hardly touches it, not from abstemiousness, but from imperious necessity. For observe that hitherto the larva has ejected no excrement and that its intestines, into which four Crickets have been crammed, are distended to bursting-point. A new ration cannot therefore tempt its gluttony; and henceforth it thinks only of making itself a silken tabernacle.
In all, its repast has lasted from ten to twelve days without cessation. At this period the larva’s length measures from twenty-five to thirty millimetres[4] and its greatest breadth from five to six.[5] Its general outline, spreading a little at the back and gradually tapering in front, conforms with the usual type of Hymenopteron-grubs. Its segments are fourteen in number, including the head, which is very [[92]]small and armed with weak mandibles that would appear unequal to the part which they have just played. Of these fourteen segments the middle ones are supplied with stigmata, or breathing-holes. Its livery consists of a yellowish-white ground, studded with innumerable dots of a chalky white.
We have seen the larva begin its second Cricket with the belly, the juiciest and softest part. Like a child, which first licks the jam off its bread and then bites into the crumb with a disdainful tooth, the larva makes straight for the best part, the abdominal viscera, and leaves until later the meat that has to be patiently extracted from its horny sheath: a task for a leisure hour, when it is comfortably digesting the earlier meal. Nevertheless, the grub, when quite young, when newly hatched, is not so dainty: it goes for the bread first and the jam afterwards. It has no choice: it is obliged to bite its first mouthful right out of the breast, at the spot where the mother fixed the egg. The food here is a little harder, but the place is safe, because of the profound inertia into which the thorax has been plunged by three thrusts of the dagger. Elsewhere there would be, if not always, at least often, spasmodic shudders which would dislodge the feeble grub and expose it to terrible hazards [[93]]among a heap of victims whose hind-legs, toothed like saws, might give an occasional jerk and whose mandibles might still be capable of snapping. It is therefore the question of safety and not of the grub’s likes or dislikes that determines the mother’s choice in placing the egg.
And here a suspicion occurs to my mind. The first ration, the Cricket on whom the egg is laid, exposes the grub to more parlous risks than do the others. To begin with, the larva is still but a frail worm; and then the victim is quite a recent one and therefore most likely to give evidence of a spark of life. This first victim has to be paralysed as completely as possible: consequently it receives the Wasp’s three dagger-thrusts. But the others, whose torpor deepens the older they grow, the others whom the larva attacks after it has gained in strength: do they need to be operated on as carefully? Might not one prick be enough, or two pricks, the effects of which would spread little by little while the grub is consuming its first ration? The poison-fluid is too precious for the Wasp to lavish it unnecessarily: it is hunting-ammunition, to be employed with due economy. At any rate, though I have witnessed three consecutive stabs given to the same victim, at other times I have seen only [[94]]two administered. It is true that the quivering tip of the Sphex’ abdomen seemed to be seeking the favourable spot for a third wound; but, if it was really given, it escaped me. I should therefore be inclined to think that the victim forming the first ration is always stabbed thrice, whereas the others, from motives of economy, receive only two stings. Our study of the Ammophilæ, who hunt Caterpillars, will confirm this suspicion later.
After devouring the last Cricket the larva sets about weaving its cocoon. The work is finished well within forty-eight hours. Henceforth the skilful worker, safe within her impenetrable shelter, can yield to the irresistible lethargy that invades her, to that nameless mode of existence, neither sleep nor waking, neither death nor life, from which she will emerge, ten months from now, transfigured. Very few cocoons are so complicated as hers. It consists, in fact, in addition to a coarse outer network, of three distinct layers, presenting the appearance of three cocoons one inside the other. Let us examine in detail these several courses of the silken edifice.
There is first an open woof, of a rough cobweb texture, whereon the larva begins by isolating itself, hanging as in a hammock, to work more easily at the cocoon proper. This [[95]]unfinished net, hastily woven to serve as a builder’s scaffolding, is made of threads flung out at random, which hold together grains of sand, bits of earth and the leavings of the larva’s feast: the Cricket’s thighs, still braided with red, his shanks and pieces of his skull. The next covering, which is the first covering of the cocoon proper, consists of a much-creased felted tunic, light-red in colour, very fine and very flexible. A few threads flung out here and there join it to the previous scaffolding and to the second wrapper. It forms a cylindrical wallet, closed on every side and too large for its contents, thus causing the surface to wrinkle.
Next comes an elastic sheath, distinctly smaller than the wallet that contains it, almost cylindrical, rounded at the upper end, towards which the larva’s head is turned, and finishing in a blunt cone at the lower end. Its colour is still light-red, save towards the cone at the bottom, where the shade is darker. Its consistency is pretty firm; nevertheless, it yields to moderate squeezing, except in its conical part, which resists the pressure of the fingers and seems to contain a hard substance. On opening this sheath, we see that it is formed of two layers closely applied one to the other, but easily separated. The outer layer is a silk [[96]]felt, exactly like that of the wallet which comes before; the inner layer, the third layer of the cocoon, is a sort of shellac, a shiny wash of a dark violet-brown, brittle, very soft to the touch, and of a nature apparently quite different from the rest of the cocoon. We see, in fact, under the microscope that, instead of being a felt of silky threads like the previous wrapper, it is a homogeneous coating of a peculiar varnish, whose origin is rather singular, as we shall see. As for the resistance of the cone-shaped end of the cocoon, we discover that this is due to a plug of crumbly matter, violet-black and sparkling with a number of black particles. This plug is the dried mass of the excrement which the larva ejects, once and for all, inside the cocoon itself. The same stercoral kernel also causes the darker shade of the cone-shaped end of the cocoon. The complicated dwelling averages twenty-seven millimetres in length, while its greatest width is nine millimetres.[6]
Let us return to the violet varnish that lines the inside of the cocoon. I thought at first that I must attribute it to the silk-glands, which, after giving a glossy coat to the double wrapper of silk and the scaffolding, have still a secret store of the fluid. To convince myself, I opened some larvæ which had just finished [[97]]their work as weavers and had not yet begun to apply their lacquer. At that period I saw no trace of violet fluid in the silk-glands. This shade is found only in the digestive canal, which bulges with a purple-coloured pulp; we find it also, but later, in the stercoral plug relegated to the lower end of the cocoon. With this exception, everything is white, or faintly tinged with yellow. Far be it from me to suggest that the larva plasters its cocoon with its excreta; and yet I am convinced that this plaster is a product of the digestive organs and I suspect, though I cannot say for certain—having been clumsy enough several times to miss a favourable opportunity of making sure—that the larva disgorges and applies with its mouth the quintessence of the purple pulp from its stomach in order to form the shellac glaze. Only after this last performance would it reject its digestive residuum in a single lump; and this would explain the unpleasant necessity in which the larva finds itself of making room for its excreta inside its actual habitation.
Be this as it may, there can be no doubt about the usefulness of the coating of shellac; its complete impermeability must protect the larva against the damp which would certainly attack it in the precarious refuge dug for it by the mother. Remember that the larva is [[98]]buried only a few inches down in uncovered, sandy ground. To judge to what extent the cocoons thus varnished are able to resist the damp, I kept some steeped in water for several days on end, without afterwards finding a trace of moisture inside them. Compare the Sphex’ cocoon, with its manifold linings, which are so well adapted for the protection of the larva in an unprotected burrow, with the cocoon of the Great Cerceris, lying under the dry shelter of a slab of sandstone and at a distance of eighteen or twenty inches underground: this cocoon has the shape of a very long pear, with the narrow end lopped off. It consists of a single silken wrapper, so thin and fine that the larva shows through it. In my numerous entomological investigations I have always seen the larva’s industry and the mother’s thus making good each other’s deficiencies. In a deep, well-sheltered abode, the cocoon is of a light material; in a surface dwelling, exposed to the inclemencies of the weather, the cocoon is stoutly built.
Nine months elapse, during which a task is performed wherein all is mystery. I skip this period, filled with the dead secret of the transformation, and, to come to the nymph, pass at once from the end of September to the first days of the following June. The larva has cast its [[99]]withered slough; the nymph, that transitory organism, or rather that perfect insect in swaddling-bands, motionlessly awaits the awakening which will not take place for another month to come. The legs, the antennæ, the exposed mouth-parts and the wing-stumps have the appearance of clearest crystal and lie evenly spread under the thorax and the abdomen. The rest of the body is an opaque white, very faintly smeared with yellow. The middle four segments of the abdomen carry a narrow and blunt extension on either side. The last segment, terminating above in a blade-like expansion shaped like the sector of a circle, is equipped below with two conical protuberances set side by side: this makes in all eleven appendages studding the outline of the abdomen. Such is the delicate creature which, to become a Sphex, must don a motley livery of black and red and throw off the fine skin in which it is closely swathed.
I was curious to follow from day to day the appearance and the progress of the nymph’s colouring and to test whether the light of the sun, that rich palette whence nature derives her colours, could influence that progress. With this object, I took pupæ from their cocoons and put them in glass tubes, of which some, kept in complete darkness, realized the natural conditions [[100]]of the nymphs and served me as a standard of comparison, while the others, hung against a white wall, received a strong diffused light throughout the day. Under these diametrically opposed conditions, the evolution of the colours remained absolutely uniform in both cases, or, if there were some slight discrepancies, these were to the disadvantage of the pupæ exposed to the light. It is, therefore, exactly the reverse of what happens in the case of plants: light does not affect the colouring of insects, does not even accelerate the process; and this must be so, because, in the species which are the most brilliant in colouring, the Buprestes and Ground-beetles, for instance, the wondrous hues which one would imagine to be stolen from a sunbeam are really elaborated in the dusky bowels of the earth or deep down in the decaying trunk of some venerable tree.
The first outlines of colour show on the eyes, whose faceted cornea changes successively from white to fawn, next to slate-grey, lastly to black. The simple eyes at the top of the forehead, the ocelli, share in this colouring, in their turn, before the rest of the body has yet lost any of its neutral, white tint. It should be remarked that this early development of the most delicate organ, the eye, is general in all animals. Later, a smoky line appears on the [[101]]upper part of the groove separating the mesothorax and the metathorax; and, twenty-four hours later, the whole back of the metathorax is black. At the same time, the edge of the prothorax becomes shaded, a black dot appears in the central and upper part of the metathorax, and the mandibles assume a rusty tinge. Gradually a deeper and deeper shade creeps over the two end segments of the thorax and finally reaches the head and the hind-quarters. A day is enough to turn the smoky hue of the head and of the end segments deep black. Thereupon the abdomen begins to share in the rapidly-increasing coloration. The edge of its front segments is tinted saffron; and its hinder segments acquire a dull-black border. Lastly, the antennæ and legs, after passing through darker and darker shades, turn black; the lower part of the abdomen is now entirely orange-red and the tip black. The livery is complete except for the tarsi and the mouth-parts, which are a transparent red, and the wing-stumps, which are dull black. In four-and-twenty hours the nymph will burst its fetters.
It takes the nymph only six or seven days to don its final tints, omitting the eyes, whose colouring precedes that of the rest of the body by fourteen or fifteen days. The law governing [[102]]the insect’s chromatic evolution is easily gathered from this brief sketch. We see that, with the exception of the eyes and the ocelli, whose early development recalls what takes place in the higher animals, the starting-point of the coloration is a central spot, the mesothorax, whence it gradually invades, by centrifugal progression, first the rest of the thorax, then the head and abdomen, lastly the different appendages, the legs and antennæ. The tarsi and the mouth-parts colour later still; and the wings do not assume their hue until after they are taken from their cases.
We now have the Sphex arrayed in her livery. She has yet to cast her nymphal wrapper. This is a very fine tunic, moulded exactly in accordance with the smallest structural details and scarcely veiling the shape and colours of the perfect insect. As a prelude to the last act of the metamorphosis, the Sphex, suddenly shaking off her torpor, begins to move about violently, as though to call her long-numbed limbs to life. The abdomen is alternately lengthened and shortened; the legs are abruptly extended, then bent, then extended again; and their different joints are stiffened with an effort. The insect, using its head and the tip of its abdomen as a lever, with the ventral surface underneath, repeatedly distends [[103]]with vigorous jerks the joint of the neck and that of the peduncle connecting the abdomen and the thorax. At last its efforts are crowned with success; and, after a quarter of an hour of these rough gymnastics, the scabbard, tugged in every direction, rips open at the neck, at the point where the legs are attached and near the peduncle of the abdomen, in short, wherever the mobility of the parts has permitted any violent dislocation to take place.
All these rents in the veil that is being cast result in a number of irregular shreds, whereof the largest envelops the abdomen and runs up the back of the thorax. To this shred belong the wing-cases. A second shred covers the head. Lastly, each leg has its own sheath, more or less badly treated near the base. The large shred, which in itself forms the best part of the wrapper, is thrown off by means of alternate contractions and expansions of the abdomen. By this mechanical process it is slowly forced backwards, where it ends by forming a little pellet that for some time remains fastened to the insect by the tracheal gills. The Sphex then once more becomes motionless; and the operation is over. However, the head, antennæ and legs are still more or less veiled. It is evident that the legs in particular cannot be freed all in one piece, [[104]]because of the numerous excrescences or spines with which they are armed. These different shreds of skin dry up on the insect and are removed afterwards by rubbing the legs. It is not until the Sphex has acquired her full vigour that she finishes her moulting by brushing, smoothing and combing her whole body with her tarsi.
The way in which the wings come out of their sheaths is the most remarkable part of the sloughing. In their incomplete stump stage they are folded lengthwise and are very much compressed. It is easy to extract them from their cases a little while before the normal date of their appearance; but then they remain permanently contracted and do not fill out. On the other hand, when once the large strip of skin to which the sheaths of the wings belong is pushed back by the movements of the abdomen, we see the wings come slowly out of their cases and straightway, as they become free, assume dimensions out of all proportion to the narrow prison whence they emerge. They are therefore the seat of an abundant rush of vital fluids which swell them and spread them out, and which, owing to the inflation which they provoke, must be the chief cause of the wings’ emergence from their cases. When newly expanded, the wings are heavy, [[105]]full of juices and of a very pale straw-colour. If the rush of the fluids takes place irregularly, we then see the end of the wing weighed down by a little yellow drop contained between the two scales.
After stripping herself of the abdominal sheath, which carries the wing-cases with it, the Sphex relapses into immobility for about three days. During this time the wings assume their normal hue, the tarsi become coloured, and the mouth-parts, at first extended, adopt their proper position. After twenty-four days spent in the nymphal stage, the insect has achieved the perfect state. It tears the cocoon that holds it captive, opens itself a passage through the sand and comes out one fine morning into the light of day, undazzled by that hitherto unknown radiance. Bathed in sunshine, the Sphex brushes her antennæ and her wings, passes and repasses her legs over her abdomen, washes her eyes with her front tarsi wetted with saliva, like a cat; and, her toilet finished, flies away joyfully: she has two months to live.
You pretty Sphex-wasps hatched before my eyes, brought up by my hand, ration by ration, on a bed of sand in an old quill-box; you whose transformations I have followed step by step, starting up from my sleep in alarm lest I should [[106]]have missed the moment when the nymph is bursting its swaddling-bands or the wing leaving its case; you who have taught me so much and learned nothing yourselves, knowing without teachers all that you have to know: O my pretty Sphex-wasps, fly away without fear of my tubes, my boxes, my bottles, or any of my receptacles, through this warm sunlight beloved of the Cicadæ;[7] go, but beware of the Praying Mantis,[8] who is plotting your ruin on the flowering heads of the thistles, and mind the Lizard, who is lying in wait for you on the sunny slopes; go in peace, dig your burrows, stab your Crickets scientifically and continue your kind, to procure one day for others what you have given me: the few moments of happiness in my life! [[107]]
[1] ·117 to ·156 inch.—Translator’s Note. [↑]
[2] A species of Green Grasshopper.—Translator’s Note. [↑]
[3] Nearly half an inch.—Translator’s Note. [↑]
[4] ·975 to 1·17 inch.—Translator’s Note. [↑]
[5] ·195 to ·234 inch.—Translator’s Note. [↑]
[6] 1·05 × ·35 inch.—Translator’s Note. [↑]
[7] Cf. Social Life in the Insect World: chaps. i. to iv.—Translator’s Note. [↑]
[8] Cf. Social Life in the Insect World: chaps. v. to vii.—Translator’s Note. [↑]
Chapter vii
ADVANCED THEORIES
The species of the genus Sphex are fairly numerous, but are for the most part strangers to my country. As far as I know, the French fauna numbers only three, all lovers of the hot sun of the olive district, namely, the Yellow-winged Sphex (Sphex flavipennis), the White-edged Sphex (S. albisecta), and the Languedocian Sphex (S. occitanica). Now it is not without a lively interest that the observer notices in the case of these three freebooters a choice of provisions which is in strict accordance with the rigid laws of entomological classification. To feed their grubs, all three choose solely Orthoptera.[1] The first hunts Crickets, the second Locusts, the third Ephippigers.
The prey selected have such great outward differences one from the other that to associate them and grasp their similarity calls for the practised eye of the entomologist or the no [[108]]less experienced eye of the Sphex. Pray compare the Cricket with the Locust: the first has a large, round, stumpy head, is short and thickset and black all over, with red stripes on his hinder thighs; the second is greyish in colour, long and slim, with a small, tapering head, leaps forward by suddenly unbending his long hind-legs and continues this flight with wings furled like a fan. Next compare both of these with the Ephippiger, who carries his musical instrument, two shrill cymbals shaped like concave scales, on his back and who waddles along with his pendulous belly, ringed pale-green and buttercup-yellow and armed with a long dirk. Place the three side by side and you will agree with me that, to guide her in choosing between such dissimilar species, while still keeping to the same entomological order, the Sphex must have an eye so expert that no man—not your ordinary layman, but a man of science—need be ashamed to own it.
In the face of these singular predilections, which seem to have had their limits laid down for them by some master of classification, by a Latreille, for instance, it becomes interesting to investigate whether the Sphex-wasps that are not natives of our country hunt game of the same order. Unfortunately, information on this point is scanty and, in the case of most [[109]]of the species, is lacking altogether. The chief cause of this regrettable lacuna is the superficial method generally adopted. People catch an insect, stick a long pin through it, fix it in the cork-bottomed box, gum a label with a Latin name underneath its feet, and let its history end there. It is not thus that I understand the duties of an entomological biographer. It is no use telling me that this or that species has so many joints to its antennæ, so many nervures to its wings, so many hairs on a region of the belly or thorax; I do not really know the insect until I am acquainted with its manner of life, its instincts and its habits.
And see the immense and luminous advantage which a description of this kind, told in two or three words, would possess over those long descriptive details, sometimes so hard to grasp. Suppose that you wish to make the Languedocian Sphex known to me and you begin by describing the number and distribution of the nervures of the wings; you speak to me of cubital nervures and recurrent nervures. Next comes the insect’s pen-portrait. Black here, rusty red there, smoky brown at the tips of the wings; black velvet in this part, silvery down in that, a smooth surface in a third. It is all very definite and minute: we must do this much justice to the precision and patience [[110]]of the narrator; but it is very long and also it is by no means always clear, so much so that we may be excused if we are not quite able to follow it, even when we are not altogether new to the business. But add to the tedious description merely this: ‘Hunts Ephippigers’; and these two words at once shed light: there is no possibility of my now mistaking my Sphex, for she alone possesses the monopoly of that particular prey. To give this illuminating note, what would be needed? The habit of really observing and of not making entomology consist of so many series of impaled insects.
But let us pass on and examine the little that is known about the hunting methods of the foreign Sphex-wasps. I open Lepeletier de Saint-Fargeau’s[2] Natural History of Hymenoptera and find that, on the other side of the Mediterranean, in our Algerian provinces, the Yellow-winged Sphex and the White-edged Sphex retain the same habits that characterize them here. They capture Orthoptera in the land of palm-trees even as they do in the land of olive-trees. Though separated from the others by the vast width of the sea, the hunting [[111]]compatriots of the Kabyles and the Berbers pursue the same game as their kindred in Provence. I also see that a fourth species, the African Sphex (S. afra), is the scourge of the Locusts in the neighbourhood of Oran. Lastly, I remember reading, I forget where, of a fifth species which also wages war on Locusts in the steppes near the Caspian. Thus, on the borders of the Mediterranean, we have five different species of Sphex, whose larvæ all live on a diet of Orthoptera.
Now let us cross the equator and go right down to the southern hemisphere, to the islands of Mauritius and Réunion: we shall here find not a Sphex, but a closely-allied Wasp of the same tribe, the Compressed Chlorion, hunting the horrible Kakerlak, that ravager of the foodstuffs in the ships and harbours of the colonies. These Kakerlaks are none other than Cockroaches, whereof one species haunts our dwellings. Who does not know the evil-smelling insect, which, thanks to its flat body, like that of a huge Bug, slips at night through the gaps in furniture and the crannies of partitions and invades any place containing provisions to be devoured? This is the Black-beetle of our houses, a disgusting counterpart of the no less disgusting prey beloved of the Chlorion. What is there about the Kakerlak [[112]]to cause him to be selected as a prey by a near cousin of our Sphex-wasps? It is quite simple: with his Bug shape, the Kakerlak also is an Orthopteron, just as much as the Cricket, the Ephippiger or the Locust. From these six examples, the only ones known to me and of such different origins, we might perhaps deduce that all the Sphex hunt Orthoptera. At any rate, without adopting so general a conclusion, we see what the food of their larvæ must be in most cases.
There is a reason for this surprising choice. What is it? What are the grounds for a diet which, within the strict limits of one entomological order, is composed here of stinking Kakerlaks, there of somewhat dry, but highly-flavoured Locusts, elsewhere again of plump Crickets or fat Ephippigers? I confess that I cannot tell, that I am absolutely in the dark; and I leave the problem to others. At the same time, we may observe that the Orthoptera are among insects what the Ruminants are among mammals. Endowed with a mighty paunch and a placid temperament, they graze contentedly and soon put on flesh. They are numerous, widely distributed and slow in movement, which renders them easy to catch; moreover, they are of a large size, making fine heads of game. Who can say if the Sphex-wasps, [[113]]powerful huntresses, requiring big prey, do not find in these Ruminants of the insect world what we ourselves find in our domestic Ruminants, the Sheep and the Ox, peaceable victims yielding plenty of flesh? It is just a possibility, but no more.
I have something better than a possibility to offer in reply to another and no less important question. Do the Orthopteron-eaters ever vary their diet? Should the favourite type of game fall short, can they not accept a different one? Does the Languedocian Sphex consider that there is nothing in the world worth having but fat Ephippigers? Does the White-edged Sphex allow none but Locusts to figure on her table; and the Yellow-winged Sphex none but Crickets? Or, according to time, place and circumstances, does each make up for the lack of her favourite victuals by others more or less equivalent? To ascertain such facts, if they exist, would be of the greatest importance, for they would tell us if the inspirations of instinct are absolute and unchangeable, or if they vary and within what limits. It is true that the cells of one and the same Cerceris contain the most varied species of either the Buprestis or the Weevil group, which shows that the huntress has a great latitude of choice; but this extension of the hunting-fields cannot be [[114]]presumed in the case of the Sphex-wasps, whom I have seen so faithful to an exclusive victim, always the same for each of them, and who moreover find, among the Orthoptera, groups that differ very widely in shape. Nevertheless, I have had the good fortune to come upon one case, one only, of complete change in the larva’s nourishment; and I record it the more willingly in the Sphegian archives inasmuch as such facts, scrupulously observed, will one day form foundation-stones for any one who cares to build up the psychology of instinct on a solid basis.
Here are the facts. The scene is enacted on a towing-path along the Rhône. On one side is the mighty stream, with its roaring waters; on the other is a thick hedge of osiers, willows, and reeds; between the two runs a narrow walk, with a carpet of fine sand. A Yellow-winged Sphex appears, hopping along, dragging her prey. What do I see! The prey is not a Cricket, but a common Acridian, a Locust! And yet the Wasp is really the Sphex with whom I am so familiar, the Yellow-winged Sphex, the keen Cricket-huntress. I can hardly believe the evidence of my own eyes.
The burrow is not far off: the insect enters it and stores away the booty. I sit down, determined to wait for a new expedition, to wait [[115]]hours if necessary, so that I may see if the extraordinary capture is repeated. My sitting attitude makes me take up the whole width of the path. Two raw conscripts heave in sight, their hair newly cut, wearing that inimitable automaton look which the first days of barrack-life bestow. They are chatting together, talking no doubt of home and the girl they left behind them; and each is innocently whittling a willow-switch with his knife. I am seized with a sudden apprehension. Ah, it is no easy matter to experiment on the public road, where, when the long-awaited event occurs at last, the arrival of a wayfarer is likely to disturb or ruin opportunities that may never return! I rise, anxiously, to make way for the conscripts; I stand back in the osier-bed and leave the narrow passage free. To do more would have been unwise. To say, ‘Don’t go this way, my good lads,’ would have made bad worse. They would have suspected some trap hidden under the sand, giving rise to questions to which no reply that I could have made would have sounded satisfactory. Besides, my request would have turned those idlers into lookers-on, very embarrassing company in such studies. I therefore got up without speaking and trusted to my lucky star. Alas and alack, my star betrayed me: the heavy regulation boot came [[116]]straight down upon the ceiling of the Sphex! A shudder ran through me as though I myself had received the impress of the hobnailed sole.
When the conscripts had passed, I proceeded to save what I could of the ruined burrow’s contents. The Sphex was there, crushed and mangled; and with her not only the Locust whom I had seen carried down, but two others as well, making three Locusts in all instead of the usual Crickets. What was the reason of this curious change? Were there no Crickets in the neighbourhood of the burrow and was the distressed Wasp making up for them with Locusts: a case of Hobson’s choice, in fact? I hesitate to believe it, for there was nothing about the neighbourhood to warrant the supposition that the favourite game was absent. Another, luckier than I, will unriddle this new and unknown mystery. The fact remains that the Yellow-winged Sphex, either from imperious necessity or for some reason that escapes me, sometimes replaces her chosen prey, the Cricket, with another prey, the Locust, presenting no external resemblance to the first, but itself also an Orthopteron.
The observer on whose authority Lepeletier de Saint-Fargeau says a word or two touching the habits of this same Sphex witnessed a similar storing away of Locusts in Africa, near [[117]]Oran. He surprised a Yellow-winged Sphex dragging an Acridian along. Was it an accidental case, like that which I witnessed on the banks of the Rhône? Was it an exception or the rule? Can there be a lack of Crickets in the country around Oran and does the Wasp fill their place with Acridians? The force of circumstances compels me to put the question without finding a reply.
This is the place to interpolate a certain passage from Lacordaire’s[3] Introduction to Entomology against which I am eager to protest. Here it is:
‘Darwin,[4] who wrote a book on purpose to prove the identity of the intellectual principle [[118]]actuating men and animals, was walking one day in his garden when he saw on the path a Sphex who had just possessed herself of a Fly almost as large as herself. He saw her cut off the victim’s head and abdomen with her mandibles, keeping only the thorax, to which the wings remained attached, after which she flew away; but a breath of wind, striking the Fly’s wings, made the Sphex spin round and prevented her progress; hereupon she alighted again on the path, cut off one of the Fly’s wings and then the other, and, after thus destroying the cause of her difficulties, resumed her flight with what remained of her prey. This fact carries with it manifest signs of reasoning power. Instinct might have led this Sphex to cut off her victim’s wings before carrying it to her nest, as do some species of the same genus; but here there was a sequence of ideas and results from those ideas, which are quite inexplicable unless we allow the intervention of reason.’
This little story, which so lightly grants reason to an insect, lacks I will not say truth, [[119]]but even mere likelihood, not in the act itself, which I accept without reserve, but in the motives for the act. Darwin saw what he tells us; only, he was mistaken as to the heroine of the drama, the drama itself and its significance. He was profoundly mistaken; and I will prove it.
First of all, the old English scientist was bound to know enough about the creatures to which he gives these high dignities to call things by their right names. Let us therefore take the word Sphex in its strict scientific meaning. Under this assumption, by what strange aberration was this English Sphex, if any such there be, choosing a Fly for her prey, when her kinswomen hunt such different game, Orthoptera? Even admitting what I consider to be inadmissible, a Fly to form the quarry of a Sphex, other difficulties come crowding up. It is now duly proved that the Burrowing Wasps do not take dead bodies to their larvæ, but a victim merely numbed, paralysed. Then what is the meaning of this prey of which the Sphex cuts off the head, the abdomen, the wings? The stump carried away is no more than a fragment of a corpse, which would infect the cell with its rottenness, without being of any use to the larva, whose hatching is not due for some days yet. It is as clear as daylight: when making [[120]]his observation, Darwin did not have before him a Sphex in the strict sense of the word. Then what did he see?
The term Fly, by which the captured prey is designated, is a very elastic word, which can be applied to the immense order of Diptera and which therefore leaves us undecided among thousands of species. The expression Sphex is most likely also employed in an equally indefinite sense. At the end of the eighteenth century, when Darwin’s book appeared, this expression was used to denote not only the Sphegidæ proper, but particularly the Crabronidæ. Now, among the latter, some, when storing provisions for their larvæ, hunt Diptera, Flies, the prey required by the unknown Hymenopteron of the English naturalist. Then was Darwin’s Sphex a Crabro? No; for these Dipteron-hunters, like the hunters of any other prey, want game that keeps fresh, motionless but half-alive, for the fortnight or three weeks required for the hatching of the eggs and the complete development of the larvæ. All these little ogres need meat killed that day and not gone bad or even a little high. This is a rule to which I know of no exception. The word Sphex cannot be accepted therefore, even with its old meaning.
Instead of a precise fact, really worthy of [[121]]science, we have a riddle to read. Let us continue to examine the riddle. Different species of the Crabro family are so like the Social Wasps in size, in shape and in their black-and-yellow livery as to deceive any eye unversed in the delicate distinctions of entomology. To any one who has not made a special study of such subjects a Crabro is a Common Wasp. May it not have happened that the English observer, looking at things from a height and thinking unworthy of strict investigation the tiny fact which nevertheless was to corroborate his transcendental theories and help to bestow reason upon an animal, made a mistake in his turn, but one in the other direction and quite pardonable, by taking a Wasp for a Crabro? I would almost dare swear so; and here are my reasons.
Wasps, if not always, at least often bring up their family on animal food; but, instead of accumulating a provision of game in each cell beforehand, they distribute the food to the larvæ, one by one and several times a day; they feed them with their mouths, as the father and mother feed young birds with their beaks. And the mouthful consists of a fine mash of chewed insects, ground between the mandibles of the Wasp nurse. The favourite insects for the preparation of this infants’ food are Diptera, [[122]]especially Common Flies; when fresh meat can be had, it is a windfall eagerly turned to account. Who has not seen Wasps boldly enter our kitchens or pounce upon the meat hanging in the butchers’ shops, to cut off a scrap that suits them and carry it away forthwith, as spolia opima for the use of the grubs? When the half-closed shutters admit a streak of sunlight to the floor of a room, where the Housefly is taking a luxurious nap or polishing her wings, who has not seen the Wasp rush in, swoop down upon the Fly, crush her in her mandibles and make off with the booty? Once again, a morsel reserved for the carnivorous nurselings.
The prey is dismembered now on the spot where captured, now on the way, now at the nest. The wings, which possess no nutritive value, are cut off and rejected; the legs, which are poor in juices, are also sometimes disdained. There remains a mutilated corpse, head, thorax, abdomen, united or separated, which the Wasp chews and rechews to reduce it to the pap beloved of the larvæ. I have tried to take the place of the nurses in this method of rearing grubs on Fly-soup. The subject of my experiment was a nest of Polistes gallica, the Wasp who fastens her little rosette of brown-paper cells to the roots of a shrub. My kitchen-table [[123]]was a flat piece of marble on which I crushed the Fly-pap after cleaning the heads of game, that is to say, after removing the parts that were too tough, the wings and legs; lastly, the feeding-spoon was a fine straw, at the tip of which the dish was served, from cell to cell, to each nurseling, which opened its mandibles just as the young birds in the nest might do. I used to go to work in exactly the same way and succeeded no better when bringing up broods of Sparrows, that joy of my childhood. All went well as long as my patience did not fail me, tried as it was by the cares of so finikin and absorbing an education.
The obscurity of the enigma gives way to the full light of truth thanks to the following observation, made with all the deliberateness which strict precision calls for. In the early days of October, two large clumps of asters in blossom outside the door of my study became the meeting-place of a host of insects, among which the Hive-bee and an Eristalis-fly (Eristalis tenax) predominate. A gentle murmur rose from them, like that of which Virgil sings:
Sæpe levi somnum suadebit inire susurro.[5]
But, where the poet finds but an incitement [[124]]to the delights of sleep, the naturalist beholds a subject for study: all this small folk making holiday on the last flowers of the year will perhaps furnish him with some fresh data. Behold me then on observation duty before the two clumps with their thousands of lilac petals.
The air is absolutely still, the sun blazing, the atmosphere heavy: signs of an approaching storm, but conditions eminently favourable to the work of the Hymenoptera, who seem to foresee to-morrow’s rain and redouble their activity to improve the opportunity. And so the Bees plunder eagerly, while the Eristales fly clumsily from flower to flower. At times, the peaceable multitude, filling its crop with nectar, is disturbed by the sudden invasion of the Wasp, a ravening insect attracted hither by prey, not honey.
Equally ardent in carnage, but very unequal in strength, two species divide the hunting between them: the Common Wasp (Vespa vulgaris), who catches Eristales, and the Hornet (Vespa crabro), who preys on Hive-bees. The methods are the same in either case. Both bandits explore the expanse of flowers with an impetuous flight, going backwards and forwards in a thousand directions, and then make a sudden rush for the coveted prey, which is on [[125]]its guard and flies away, while the kidnapper’s impetus brings her up with a bump against the deserted flower. Then the pursuit continues in the air, as though a Sparrow-hawk were chasing a Lark. But the Bee and the Eristalis, by taking brisk turns, soon baffle the attempts of the Wasp, who resumes her evolutions above the clustering blossoms. At last, sooner or later, some quarry less quick at flight is captured. Forthwith, the Common Wasp drops on to the lawn with her Eristalis; I also instantly lie on the ground, quietly removing with my hands the dead leaves and bits of grass that might interfere with my view; and I witness the following tragedy, if I have taken proper precautions not to scare the huntress.
First, there is a wild struggle in the tangle of the grass between the Wasp and the Eristalis, who is bigger than her assailant. The Fly is unarmed, but powerful; a shrill buzz of her wings tells of her desperate resistance. The Wasp carries a dagger; but she does not understand the methodical use of it, is unacquainted with the vulnerable points so well known to the marauders who need a prey that keeps fresh for long. What her nurselings want is a mess of Flies that moment reduced to pulp; and, so long as this is achieved, the Wasp cares little how the game is killed. The sting therefore [[126]]is used blindly, without any method. We see it pointed indifferently at the victim’s back, sides, head, thorax, or belly, according to the chances of the scuffle. The Hunting Wasp paralysing her victim acts like a surgeon who directs his scalpel with a skilled hand; the Social Wasp killing her prey behaves like a common assassin who stabs at random. For this reason the Eristalis’ resistance is prolonged; and her death is the result of scissor-cuts rather than dagger-thrusts. When the victim is duly garrotted, motionless between its ravisher’s legs, the head falls under a snap of the mandibles; then the wings are cut off at their juncture with the shoulder; the legs follow, severed one by one; lastly, the belly is flung aside, but emptied of the entrails, which the Wasp appears to add to the one favoured portion. This choice morsel is solely the thorax, which is richer in lean meat than the rest of the Eristalis’ body. Without further delay the Wasp flies off with it, carrying it in her legs. On reaching the nest, she will make it into potted Fly and serve it in mouthfuls to the larvæ.
The Hornet who has caught a Bee acts in much the same manner; but, in the case of an assailant of her dimensions, the struggle cannot last long, notwithstanding the victim’s sting. [[127]]The Hornet may prepare her dish on the very flower where the capture was effected, or more often on some twig of an adjacent shrub. The Bee’s crop is first ripped open and the honey that runs out of it lapped up. The prize is thus a twofold one: a drop of honey for the huntress to feast upon and the Bee herself for the larvæ. Sometimes the wings are removed and also the abdomen; but generally the Hornet is satisfied with reducing the Bee to a shapeless mass, which she carries off without disdaining anything. Those parts which have no nutritive value, especially the wings, will be rejected on arriving at the nest. Lastly, she sometimes prepares the mash in the actual hunting-field, that is to say, she crushes the Bee between her mandibles after removing the wings, the legs, and at times the abdomen as well.
Here then, in all its details, is the incident observed by Darwin. A Wasp (Vespa vulgaris) catches a big Fly (Eristalis tenax); she cuts off the victim’s head, wings, abdomen, and legs with her mandibles and keeps only the thorax, which she carries off flying. But here there is not the least breath of wind to explain the carving process; besides, the thing happens in a perfect shelter, in the thick tangle of the grass. The butcher rejects such parts of her [[128]]prey as she considers valueless to her larvæ; and that is all about it.
In short, the heroine of Darwin’s story is certainly a Wasp. Then what becomes of that rational calculation on the part of the insect which, the better to contend with the wind, cuts off its prey’s abdomen, head and wings and keeps only the thorax? It becomes a most simple incident, leading to none of the mighty consequences which the writer seeks to deduce from it: the very trivial incident of a Wasp who begins to carve up her prey on the spot and keeps only the stump, the one part which she considers fit for her larvæ. Far from seeing the least sign of reason in this, I look upon it as a mere act of instinct, one so elementary that it is really not worth expatiating upon.
To disparage man and exalt animals in order to establish a point of contact, followed by a point of union, has been and still is the general tendency of the ‘advanced theories’ in fashion in our day. Ah, how often are these ‘sublime theories,’ that morbid craze of the time, based upon ‘proofs’ which, if subjected to the light of experiment, would lead to as ridiculous results as the learned Erasmus Darwin’s Sphex! [[129]]
[1] The order of insects including Earwigs, Cockroaches, Mantes, Crickets, Locusts and Grasshoppers.—Translator’s Note. [↑]
[2] Amédée Comte Lepeletier de Saint-Fargeau (1769–circa 1850), author of an Histoire naturelle des insectes (1836–1846) and of the volume on insects in the Encyclopédie méthodique. He was a younger brother of Louis Michel and Félix Lepeletier de Saint-Fargeau, the members of the Convention.—Translator’s Note. [↑]
[3] Jean Théodore Lacordaire (1801–1870), professor at the university of Liège from 1835, author of Les Genera des coléoptères, in twelve volumes, and of the Introduction à l’entomologie quoted above (1837–1839).—Translator’s Note. [↑]
[4] Erasmus Darwin (1731–1802), the poet and naturalist, grandfather of Charles Robert Darwin. The book from which the above passage is quoted is Zoonomia, or, The Laws of Organic Life (1794–1796); but the reader will note that the author withdraws these comments in a later essay (cf. The Mason-bees, by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chap. vii.), where he explains that they are due to a misquotation or mistranslation made by Lacordaire, who wrote ‘a Sphex’ where Darwin, as his grandson pointed out to Fabre, had written ‘a Wasp,’ meaning the Common or Social Wasp. It was open to me to suppress this part of the chapter; but, in that case, there would have been so little left of the original and so small an excuse for the title that I might as readily have suppressed the whole chapter, a liberty which I did [[118]]not feel justified in taking. Besides, the footnote to the aforementioned chapter of The Mason-bees, which precedes the present volume in the English edition, makes sufficient amends for any injury done to the elder Darwin’s reputation here.—Translator’s Note. [↑]
‘The busy bees, with a soft murmuring strain,
Invite to gentle sleep the labouring swain.’—
Pastorals, i., Dryden’s translation. [↑]
Chapter viii
THE LANGUEDOCIAN SPHEX
When the chemist has fully prepared his plan of research, he mixes his reagent at the most convenient moment and lights a flame under his retort. He is the master of time, place and circumstances. He chooses his hour, shuts himself up in his laboratory, where nothing can come to disturb the business in hand; he produces at will this or that condition which reflection suggests to him: he is in quest of the secrets of inorganic matter, whose chemical activities science can awaken whenever it thinks fit.
The secrets of living matter—not those of anatomical structure, but really those of life in action, especially of instinct—present much more difficult and delicate conditions to the observer. Far from being able to choose his own time, he is the slave of the season, of the day, of the hour, of the very moment. When the opportunity offers, he must seize it as it comes, without hesitation, for it may be long [[130]]before it presents itself again. And, as it usually arrives at the moment when he is least expecting it, nothing is in readiness for making the most of it. He must then and there improvise his little stock of experimenting material, contrive his plans, evolve his tactics, devise his tricks; and he can think himself lucky if inspiration comes fast enough to allow him to profit by the chance offered. This chance, moreover, hardly ever comes except to those who look for it. You must watch for it patiently for days and days, now on sandy slopes exposed to the full glare of the sun, now on some path walled in by high banks, where the heat is like that of an oven, or again on some sandstone ledge which is none too steady. If it is in your power to set up your observatory under a meagre olive-tree that pretends to protect you from the rays of a pitiless sun, you may bless the fate that treats you as a sybarite: your lot is an Eden. Above all, keep your eyes open. The spot is a good one; and—who knows?—the opportunity may come at any moment.
It came—late, it is true; but still it came. Ah, if you could now observe at your ease, in the quiet of your study, with nothing to distract your mind from your subject, far from the profane wayfarer who, seeing you so busily [[131]]occupied at a spot where he sees nothing, will stop, overwhelm you with queries, take you for some water-diviner, or—a graver suspicion this—regard you as some questionable character searching for buried treasure and discovering by means of incantations where the old pots full of coin lie hidden! Should you still wear a Christian aspect in his eyes, he will approach you, look to see what you are looking at, and smile in a manner that leaves no doubt as to his poor opinion of people who spend their time in watching Flies. You will be lucky indeed if the troublesome visitor, with his tongue in his cheek, walks off at last without disturbing things and without repeating in his innocence the disaster brought about by my two conscripts’ boots.
Should your inexplicable doings not puzzle the passer-by, they will be sure to puzzle the village keeper, that uncompromising representative of the law in the ploughed acres. He has long had his eye on you. He has so often seen you wandering about, like a lost soul, for no appreciable reason; he has so often caught you rooting in the ground, or, with infinite precautions, knocking down some strip of wall in a sunken road, that in the end he has come to look upon you with dark suspicion. You are nothing to him but a gipsy, a tramp, [[132]]a poultry-thief, a shady person or, at the best, a madman. Should you be carrying your botanizing-case, it will represent to him the poacher’s ferret-cage; and you would never get it out of his head that, regardless of the game-laws and the rights of landlords, you are clearing all the neighbouring warrens of their rabbits. Take care. However thirsty you may be, do not lay a finger on the nearest bunch of grapes: the man with the municipal badge will be there, delighted to have a case at last and so to receive an explanation of your highly perplexing behaviour.
I have never, I can safely say, committed any such misdemeanour; and yet, one day, lying on the sand, absorbed in the details of a Bembex’ household, I suddenly heard beside me:
‘In the name of the law, I arrest you! You come along with me!’
It was the keeper of Les Angles, who, after vainly waiting for an opportunity to catch me at fault and being daily more anxious for an answer to the riddle that was worrying him, at last resolved upon the brutal expedient of a summons. I had to explain things. The poor man seemed anything but convinced:
‘Pooh!’ he said. ‘Pooh! You will never make me believe that you come here and roast in the sun just to watch Flies. I shall keep an [[133]]eye on you, mark you! And, the first time I …! However, that’ll do for the present.’
And he went off. I have always believed that my red ribbon had a good deal to do with his departure. And I also put down to that red ribbon certain other little services by which I benefited during my entomological and botanical excursions. It seemed to me—or was I dreaming?—it seemed to me that, on my botanizing expeditions up Mont Ventoux, the guide was more tractable and the donkey less obstinate.
The aforesaid bit of scarlet ribbon did not always spare me the tribulations which the entomologist must expect when experimenting on the public way. Here is a characteristic example. Ever since daybreak I have been ambushed, sitting on a stone, at the bottom of a ravine. The subject of my matutinal visit is the Languedocian Sphex. Three women, vine-pickers, pass in a group, on the way to their work. They give a glance at the man seated, apparently absorbed in reflection. At sunset, the same pickers pass again, carrying their full baskets on their heads. The man is still there, sitting on the same stone, with his eyes fixed on the same place. My motionless attitude, my long persistency in remaining at that deserted spot, must have impressed them [[134]]deeply. As they passed by me, I saw one of them tap her forehead and heard her whisper to the others:
‘Un paouré inoucènt, pécaïre!’
And all three made the sign of the Cross.
An innocent, she had said, un inoucènt, an idiot, a poor creature, quite harmless, but half-witted; and they had all made the sign of the Cross, an idiot being to them one with God’s seal stamped upon him.
‘How now!’ thought I. ‘What a cruel mockery of fate! You, who are so laboriously seeking to discover what is instinct in the animal and what is reason, you yourself do not even possess your reason in these good women’s eyes! What a humiliating reflection!’
No matter: pécaïre, that expression of supreme compassion, in the Provençal dialect, pécaïre, coming from the bottom of the heart, soon made me forget inoucènt.
It is in this ravine with its three grape-gathering women that I would meet the reader, if he be not discouraged by the petty annoyances of which I have given him a foretaste. The Languedocian Sphex frequents these points, not in tribes congregating at the same spot when nest-building work begins, but as solitary individuals, sparsely distributed, settling wherever the chances of their vagabondage lead [[135]]them. Even as her kinswoman, the Yellow-winged Sphex, seeks the society of her kind and the animation of a yard full of workers, the Languedocian Sphex prefers isolation, quiet and solitude. Graver of gait, more formal in her manners, of a larger size and also more sombrely clad, she always lives apart, not caring what others do, disdaining company, a genuine misanthrope among the Sphegidæ. The one is sociable, the other is not: a profound difference which in itself is enough to characterize them.
This amounts to saying that, with the Languedocian Sphex, the difficulties of observation increase. No long-meditated experiment is possible in her case; nor, when the first attempts have failed, can one hope to try them again, on the same occasion, with a second or a third subject and so on. If you prepare the materials for your observation in advance, if, for instance, you have in reserve a piece of game which you propose to substitute for that of the Sphex, it is to be feared, nay, it is almost certain that the huntress will not appear; and, when she does come at last, your materials are no longer fit for use and everything has to be improvised in a hurry, that very moment, under conditions that are not always satisfactory.
Let us take heart. The site is a first-rate one. Many a time already I have surprised [[136]]the Sphex here, sunning herself on a vine-leaf. The insect, spread out flat, is basking voluptuously in the heat and light. From time to time it has a sort of frenzied outburst of pleasure: it quivers with content; it rapidly taps its feet on its couch, producing a tattoo not unlike that of rain falling heavily on the leaf. The joyous thrum can be heard several feet away. Then immobility begins again, soon followed by a fresh nervous commotion and by the whirling of the tarsi, a symbol of supreme felicity. I have known some of these passionate sun-lovers suddenly to leave the work-yard, when the larva’s cave has been half-dug, and go to the nearest vine to take a bath of heat and light, after which they would come back to the burrow, as though reluctantly, just to give a perfunctory sweep and soon end by knocking off work, unable to resist the exquisite temptation of luxuriating on the vine-leaves.
It may be that the voluptuous couch is also an observatory, whence the Wasp surveys the surrounding country in order to discover and select her prey. Her exclusive game is the Ephippiger of the Vine, scattered here and there on the branches or on any brambles hard by. The joint is a substantial one, especially as the Sphex favours solely the females, whose bellies are swollen with a mighty cluster of eggs. [[137]]
Let us take no notice of the repeated trips, the fruitless searches, the tedium of frequent long waiting, but rather present the Sphex suddenly to the reader as she herself appears to the observer. Here she is, at the bottom of a sunken road with high, sandy banks. She comes on foot, but gets help from her wings in dragging her heavy prize. The Ephippiger’s antennæ, long and slender as threads, are the harnessing-ropes. Holding her head high, she grasps one of them in her mandibles. The antenna gripped passes between her legs; and the game follows, turned over on its back. Should the soil be too uneven and so offer resistance to this method of carting, the Wasp clasps her unwieldy burden and carries it with very short flights, interspersed, as often as possible, with journeys on foot. We never see her undertake a sustained flight, for long distances, holding the game in her legs, as is the practice of those expert aviators, the Bembeces and Cerceres, for instance, who bear through the air for more than half a mile their respective Flies or Weevils, a very light booty compared with the huge Ephippiger. The overpowering weight of her capture compels the Languedocian Sphex to make the whole, or nearly the whole, journey on foot, her method of transport being consequently slow and laborious. [[138]]
The same reason, the bulk and weight of the prey, have entirely reversed the usual order which the Burrowing Wasps follow in their operations. This order we know: it consists in first digging a burrow and then stocking it with provisions. As the victim is not out of proportion to the strength of the spoiler, it is quite simple to carry it flying, which means that the Wasp can choose any site that she likes for her dwelling. She does not mind how far afield she goes for her prey: once she has captured her quarry, she comes flying home at a speed which makes questions of distance quite immaterial. Hence she prefers as the site for her burrow the place where she herself was born, the place where her forbears lived; she here inherits deep galleries, the accumulated work of earlier generations; and, by repairing them a little, she makes them serve as approaches to new chambers, which are in this way better protected than they would be if they depended upon the labours of a single Wasp, who had to start boring from the surface each year. This happens, for instance, in the case of the Great Cerceris and the Bee-eating Philanthus. And, should the ancestral abode not be strong enough to withstand the rough weather from one year to the next and to be handed down to the offspring, should the burrower have each time [[139]]to start her tunnelling afresh, at least the Wasp finds greater safety in places consecrated by the experience of her forerunners. Consequently she goes there to dig her galleries, each of which serves as a corridor to a group of cells, thus effecting an economy in the aggregate labour expended upon the whole business of the laying.
In this way are formed not real societies, for there are no concerted efforts towards a common object, but at least assemblies where the sight of her kinswomen and her neighbours doubtless puts heart into the labour of the individual. We can observe, in fact, between these little tribes, springing from the same stock, and the burrowers who do their work alone, a difference in activity which reminds us of the emulation prevailing in a crowded yard and the indifference of labourers who have to work in solitude. Action is contagious in animals as in men; it is fired by its own example.
To sum up: when of a moderate weight for its captor, the prey can be conveyed flying, to a great distance. The Wasp can then choose any site that she pleases for her burrow. She adopts by preference the spot where she was born and uses each passage as a common corridor giving access to several cells. The result of this meeting at a common birthplace is the formation of groups, like turning to like, which [[140]]is a source of friendly rivalry. This first step towards social life comes from facilities for travelling. Do not things happen in the same way with man, if I may be permitted the comparison? When he has nothing but trackless paths, man builds a solitary hut; when supplied with good roads, he and his fellows collect in populous cities; when served by railways which, so to speak, annihilate distance, they assemble in those immense human hives called London or Paris.
The situation of the Languedocian Sphex is just the reverse. Her prey is a heavy Ephippiger, a single dish representing by itself the sum total of provisions which the other freebooters amass on numerous journeys, insect by insect. What the Cerceres and the other plunderers strong on the wing accomplish by dividing the labour she does in a single journey. The weight of the prey makes any distant flight impossible; it has to be brought home slowly and laboriously, for it is a troublesome business to cart things along the ground. This alone makes the site of the burrow dependent on the accidents of the chase: the prey comes first and the dwelling next. So there is no assembling at a common meeting-place, no association of kindred spirits, no tribes stimulating one another in their work [[141]]by mutual example, but isolation in the particular spot where the chances of the day have taken the Sphex, solitary labour, carried on without animation though with unfailing diligence. First of all, the prey is sought for, attacked, reduced to helplessness. Not until after that does the digger trouble about the burrow. A favourable place is chosen, as near as possible to the spot where the victim lies, so as to cut short the tedious work of transport; and the chamber of the future larva is rapidly hollowed out and at once receives the egg and the victuals. There you have an example of the inverted method of the Languedocian Sphex, a method, as all my observations go to prove, diametrically opposite to that of the other Hymenoptera. I will give some of the more striking of these observations.
When caught digging, the Languedocian Sphex is always alone, sometimes at the bottom of a dusty recess left by a stone that has dropped out of an old wall, sometimes ensconced in the shelter formed by a flat, projecting bit of sandstone, a shelter much sought after by the fierce Eyed Lizard to serve as an entrance-hall to his lair. The sun beats full upon it; it is an oven. The soil, consisting of old dust that has fallen little by little from the roof, is very easy to dig. The cell is soon scooped out with the mandibles, [[142]]those pincers which are also used for digging, and the tarsi, which serve as rubbish-rakes. Then the miner flies off, but with a slow flight and no sudden display of wing-power, a manifest sign that the insect is not contemplating a distant expedition. We can easily follow it with our eyes and perceive the spot where it alights, usually ten or twelve yards away. At other times it decides to walk. It goes off and makes hurriedly for a spot where we will have the indiscretion to follow it, for our presence does not trouble it at all. On reaching its destination, either on foot or on the wing, it looks round for some time, as we gather from its undecided attitude and its journeys hither and thither. It looks round; at last it finds or rather retrieves something. The object recovered is an Ephippiger, half-paralysed, but still moving her tarsi, antennæ and ovipositor. She is a victim which the Sphex certainly stabbed not long ago with a few stings. After the operation the Wasp left her prey, an embarrassing burden amid the suspense of house-hunting; she abandoned it perhaps on the very spot where she captured it, contenting herself with making it more or less conspicuous by placing it on some grass-tuft, in order to find it more easily later; and, trusting to her good memory to return presently to the spot where [[143]]the booty lies, she set out to explore the neighbourhood with the object of finding a suitable site and there digging a burrow. Once the home was ready, she came back to her prize, which she found again without much hesitation, and she now prepares to lug it home. She bestrides the victim, seizes one or both of the antennæ, and off she goes, tugging and dragging with all the strength of her loins and jaws.
Sometimes she has only to make one journey; at other times and more often, the carter suddenly plumps down her load and quickly runs home. Perhaps it occurs to her that the entrance-door is not wide enough to admit so substantial a morsel; perhaps she remembers some lack of finish that might hamper the storing. And, in point of fact, the worker does touch up her work: she enlarges the doorway, smooths the threshold, strengthens the ceiling. It is all done with a few strokes of the tarsi. Then she returns to the Ephippiger, lying yonder, on her back, a few steps away. The hauling begins again. On the road, the Sphex seems struck with a new idea, which flashes through her quick brain. She has inspected the door, but has not looked inside. Who knows if all is well in there? She hastens to see, dropping the Ephippiger before she goes. The interior is inspected; and apparently a few [[144]]pats of the trowel are administered with the tarsi, giving a last polish to the walls. Without lingering too long over these delicate after-touches, the Wasp goes back to her booty and harnesses herself to its antennæ. Forward! Will the journey be completed this time? I would not answer for it. I have known a Sphex, more suspicious than the others, perhaps, or more neglectful of the minor architectural details, to repair her omissions, to dispel her doubts, by abandoning her prize on the way five or six times running, in order to hurry to the burrow, which each time was touched up a little or merely inspected within. It is true that others make straight for their destination, without even stopping to rest. I must also add that, when the Wasp goes home to improve the dwelling, she does not fail to give a glance from a distance every now and then at the Ephippiger over there, to make sure that nothing has happened to her. This solicitude recalls that of the Sacred Beetle when he leaves the hall which he is excavating in order to come and feel his beloved pellet and bring it a little nearer to him.
The inference to be drawn from the details which I have related is manifest. The fact that every Languedocian Sphex surprised in her mining operations, even though it be at [[145]]the very beginning of the digging, at the first stroke of the tarsus in the dust, afterwards, when the home is prepared, makes a short excursion, now on foot, anon flying, and invariably finds herself in possession of a victim already stabbed, already paralysed, compels us to conclude, in all certainty, that this Wasp does her work as a huntress first and as a burrower after, so that the place of the capture decides the place of the home.
This reversal of procedure, which causes the food to be prepared before the larder, whereas hitherto we have seen the larder come before the food, I attribute to the weight of the Sphex’ prey, a prey which it is not possible to carry far through the air. It is not that the Languedocian Sphex is ill-built for flight: on the contrary, she can soar magnificently; but the prey which she hunts would weigh her down if she had no other support than her wings. She needs the support of the ground for her hauling-work, in which she displays wonderful strength. When laden with her prey, she always goes afoot, or takes but very short flights, even under conditions when flight would save her time and trouble. I will quote an instance taken from my latest observations on this curious Wasp.
A Sphex appears unexpectedly, coming I [[146]]know not whence. She is on foot, dragging her Ephippiger, a capture which apparently she has made that moment in the neighbourhood. In the circumstances it behoves her to dig herself a burrow. The site is as bad as bad can be. It is a well-beaten path, hard as stone. The Sphex, who has no time to make laborious excavations, because the already captured prize must be stored as quickly as possible, the Sphex wants soft ground, wherein the larva’s chamber can be contrived in one short spell of work. I have described her favourite soil, namely, the dust of years which has accumulated at the bottom of some hole in a wall or of some little shelter under the rocks. Well, the Sphex whom I am now observing stops at the foot of a house with a newly-whitewashed front some twenty to twenty-five feet high. Her instinct tells her that up there, under the red tiles of the roof, she will find nooks rich in old dust. She leaves her prey at the foot of the house and flies up to the roof. For some time I see her looking here, there, and everywhere. After finding a proper site, she begins to work under the curve of a pantile. In ten minutes, or fifteen at most, the home is ready. The insect now flies down again. The Ephippiger is promptly found. She has to be taken up. Will this be done on the wing, as [[147]]circumstances seem to demand? Not at all. The Sphex adopts the toilsome method of scaling a perpendicular wall, with a surface smoothed by the mason’s trowel and measuring twenty to twenty-five feet in height. Seeing her take this road, dragging the game between her legs, I at first think the feat impossible; but I am soon reassured as to the outcome of the bold attempt. Getting a foothold on the little roughnesses in the mortar, the plucky insect, despite the hindrance of her heavy load, walks up this vertical plane with the same assured gait and the same speed as on level ground. The top is reached without the least accident; and the prey is laid temporarily on the edge of the roof, upon the rounded back of a tile. While the digger gives a finishing touch to the burrow, the badly-balanced prey slips and drops to the foot of the wall. The thing must be done all over again and once more by laboriously climbing the height. The same mistake is repeated. Again the prey is incautiously left on the curved tile, again it slips and again it falls to the ground. With a composure which accidents such as these cannot disturb, the Sphex for the third time hoists up the Ephippiger by scaling the wall and, better advised, drags her forthwith right into the home.
As even under these conditions no attempt [[148]]has been made to carry the prey on the wing, it is clear that the Wasp is incapable of long flight with so heavy a load. To this incapacity we owe the few characteristics that form the subject of this chapter. A quarry that is not too big to permit the effort of flying makes of the Yellow-winged Sphex a semisocial species, that is to say, one seeking the company of her fellows; a quarry too heavy to carry through the air makes of the Languedocian Sphex a species vowed to solitary labour, a sort of savage disdainful of the pleasures that come from the proximity of one’s kind. The lighter or heavier weight of the game selected here determines the fundamental character of the huntress. [[149]]