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THE MINOR HORRORS
OF WAR

Photograph of enlarged model of the house-fly (Musca domestica) in the American Museum of Natural History, New York. (From Gordon Hewitt.) P. 57.

[Frontispiece

THE MINOR HORRORS
OF WAR

BY

A. E. SHIPLEY, Sc.D.

Hon.Sc.D. Princeton, F.R.S.

MASTER OF CHRIST’S COLLEGE, CAMBRIDGE, AND READER IN ZOOLOGY
IN THE UNIVERSITY

ILLUSTRATED

LONDON

SMITH, ELDER & CO., 15 WATERLOO PLACE

1915

[All rights reserved]

HENRICO ARTHURO ADEANE MALLET

ET

HENRICO ANTONIO PATRICIO DISNEY

ALTERI MARI AERE ALTERI

UTRIQUE FIDELISSIME

PATRIAM TUTANTI

PREFACE

The contents of this little book hardly justify its title. There are whole ranges of ‘Minor Horrors of War’ left untouched in the following chapters. The minor poets, the pamphlets of the professors, the people who write to the papers about ‘Kultur’ and think that this is the German for Matthew Arnold’s over-worked word ‘Culture,’ the half-hysterical ladies who offer white feathers to youths whose hearts are breaking because medical officer after medical officer has refused them the desire of their young lives to serve their country. Surely, as Carlyle taught us, ‘There is no animal so strange as man!’

These ‘Minor Horrors of War,’ and many besides, have for the moment been neglected in favour of certain others which attack the bodies, the food, or the accoutrements of the men who are giving all that they have to give, even unto their lives, for their homes and for their country.

I deal with certain little Invertebrata: animals which work in darkness and in stealth, little animals which in times of Peace we politely ignore, yet little animals which in times of War may make or unmake an army corps. As that wise old Greek, Aristotle, wrote—and he knew quite a lot about them—‘One should not be childishly contemptuous of the study of the most insignificant animal. For there is something marvellous in all natural objects.’

We are shy of mentioning these organisms in times of Peace; but all of them are within the cognisance of every medical officer of health and of every police-court missionary. These gentlemen do not talk about them in general society: the subject is as a rule ‘taboo.’ Yet if we face these troubles with courage and frankness, they can be overcome. As ‘Emigration Jane’ says: ‘Well, there’s nothink lower than Nature, an’ She Goes as ’Igh as ’Eaven.’

I confess that these articles have been written in a certain spirit of gaiety. This is the reflex of the spirit of those who have gone to the Front and of my fellow countrymen in general. For more years than I care to remember, the spirit of Great Britain and of Ireland had been sombre, self-distrusting—we were till half a year ago far too ‘conscious of each other’s infirmities’; but with the outbreak of the War everything changed. Our nearest relatives, our dearest friends, are dead, or dying, or wounded, or prisoners; but we at home at once caught the spirit of those who have died or have suffered for us abroad, and we have kept and still keep a high heart. As Mrs. Aberdeen, the immortal ‘bedmaker’ at King’s College, Cambridge, said: But surely, Miss, the world being what it is, the longer one is able to laugh in it, the better.’ Mrs. Aberdeen spoke in times of Peace; but I feel that that indomitable old lady would have said the same in times of War.

These chapters first appeared in the columns of the British Medical Journal. I very gratefully thank the editor and the proprietors of that Journal for their permission to reprint them.

A. E. SHIPLEY.

Christ’s College Lodge,
Cambridge.

February 14, 1915.

CONTENTS

ILLUSTRATIONS

THE

MINOR HORRORS OF WAR

CHAPTER I

THE LOUSE (Pediculus)

Care’ll kill a cat, up-tailles all and a louse for the hangman!

(B. Jonson, Every Man in his Humour.)

Lice form a small group of insects known as the Anoplura, interesting to the entomologist because they are now entirely wingless, though it is believed that their ancestry were winged. They are all parasites on vertebrates. In quite recent books the Anoplura are described as ‘lice or disgusting insects, about which little is known’; but lately, owing to researches carried on at Cambridge, we have found out something about their habits. As lice play a large part in the minor discomforts of an army, it is worth while considering for a moment what we know about them.

Fig. 1.—Pediculus vestimenti (Nitzsch). A, Magnified 20 times; B, natural size.

Recently, the group has been split up into a large number of genera, but of these only two have any relation to the human body. I do not propose, in the present chapter, to consider one of these two genera—Phthirius—which frequents the hairs about the pubic region of man and is conveyed from one human being to another by personal contact. We will confine our attention to the second genus, Pediculus, which contains two species parasitic upon man—(Pediculus capitis) the hair-louse and (Pediculus vestimenti) the body-louse. Both of these are extremely difficult to rear in captivity, though in their natural state they abound and multiply to an amazing degree.

Wherever human beings are gathered together in large numbers, with infrequent opportunities of changing their clothes, P. vestimenti is sure to spread. It does not arise, as the uninformed think, from dirt, though it flourishes best in dirty surroundings. No specimen of P. vestimenti exists which is not the direct product of an egg laid by a mother-louse and fertilised by a father-louse. In considerable collections of men drawn from the poorer classes, some unhappy being or other—often through no fault of his own—will turn up in the community with lice on him, and these swiftly spread to others in a manner that will be indicated later in this chapter.

Like almost all animals lower than the mammals, the male of the body-louse is smaller and feebler than the female. The former attains a length of about 3 mm., and is about 1 mm. broad. The female is about 3·3 mm. long and about 1·4 mm. broad. It is rather bigger than the hair-louse, and its antennae are slightly longer. It so far flatters its host as to imitate the colour of the skin upon which it lives; and Andrew Murray gives a series of gradations between the black louse of the West African and Australian native, the dark and smoky louse of the Hindu, the orange of the Africander and of the Hottentot, the yellowish-brown of the Japanese and Chinese, the dark-brown of the North and South American Indians, and the paler-brown of the Esquimo, which approaches the light dirty-grey colour of the European parasites.

As plump an’ grey as onie grozet,

as Burns has it.

The latter were the forms dealt with in the recent observations undertaken by Mr. C. Warburton in the Quick Laboratory at Cambridge, at the request of the Local Government Board, the authorities of which were anxious to find out whether the flock used in making cheap bedding was instrumental in distributing vermin. Mr. Warburton at once appreciated the fact that he must know the life-history of the insect before he could successfully attack the problem put before him. At an early stage of his investigations, he found that P. vestimenti survives longer under adverse conditions than P. capitis, the head-louse.

The habitat of the body-louse is that side of the under-clothing which is in contact with the body. The louse, which sucks the blood of its host at least twice a day, is when feeding always anchored to the inside of the under-clothing of its host by the claws of one or more of its six legs. Free lice are rarely found on the skin in western Europeans; but doctors who have recently returned from Serbia report dark-brown patches, as big as half-crowns, on the skins of the wounded natives, which on touching begin to move—a clotted scab of lice! But the under-side of a stripped shirt is often alive with them.

After a great many experiments, Mr. Warburton succeeded in rearing these delicate insects, but only under certain circumscribed conditions: one of which was their anchorage in some sort of flannel or cloth, and the second was proximity to the human skin. He anchored his specimens on small pieces of cloth which he interned in small test-tubes plugged with cotton-wool, which did not let the lice out, but did let air and the emanations of the human body in. For fear of breakage the glass tube was enclosed in an outer metal tube, and the whole was kept both night and day near the body. Two meals a day were necessary to keep the lice alive. When feeding, the pieces of cloth, which the lice would never let go of, were placed on the back of the hand, hence the danger of escape was practically nil, and once given access to the skin the lice fed immediately and greedily.

His success in keeping lice alive was but the final result of many experiments, the majority of which had failed. Lice are very difficult to rear. When you want them to live they die; and when you want them to die they live, and multiply exceedingly.

Fig. 2.—Pediculus vestimenti. Dorsal and ventral views.

A single female but recently matured was placed in a test-tube, and a male admitted to her on the second day. The two paired on the sixth day and afterwards at frequent intervals. Very soon after pairing an egg was laid, and during the remaining twenty-five days of her life the female laid an average of five eggs every twenty-four hours. The male died on the seventeenth day, and a second male was then introduced, who again paired with the female. The latter, however, died on the thirtieth day, but the second male survived.

The difficulty of keeping the male and female alive was simple compared with the difficulty of rearing the eggs. Very few hatched out. The strands of cloth upon which they were laid had been carefully removed and placed in separate tubes, at the same time being subjected to different temperatures. It was not, however, until the eggs were left alone undisturbed in the position where they had been laid and placed under the same conditions that the mother lived in that eight, and only eight, of the twenty-four eggs laid on the cloth hatched out after an incubation period of eight days. The remaining sixteen eggs were apparently dead. But the tube in which they were was then subjected to normal temperature of the room at night (on occasions this fell below freezing-point), and after an incubation period of upwards of a month six more hatched out. Hence it is obvious that, as in the case of many other insects, temperature plays a large part in the rate of development, and it becomes clear that the eggs or nits of P. vestimenti are capable of hatching out up to a period of at least from thirty-five to forty days after they are laid.

Difficult as it was to keep the adults alive, and more difficult as it was to hatch out the eggs, it was most difficult to rear the larvae. Their small size made them difficult to observe, and, like most young animals, they are intolerant of control, apt to wander and explore, and less given to clinging to the cloth than their more sedentary parents. Naturally, they want to scatter, spread themselves, and pair.

Like young chickens, the larvae feed immediately on emerging from the egg. They apparently moult three times, at intervals of about four days, and on the eleventh day attain their mature form, though they do not pair until four or five days later.

Mr. Warburton summarises the life-cycle of the insects, as indicated by his experiments, as follows:—

Incubation period: eight days to five weeks.
From larva to imago: eleven days.
Non-functional mature condition: four days.
Adult life: male, three weeks; female, four weeks.

But we must not forget that these figures are based upon laboratory experiments, and that under the normal conditions the rate may be accelerated. From Mr. Warburton’s experience it is perfectly obvious that, unless regularly fed, body-lice very quickly die. Of all the verminous clothing sent to the Quick Laboratory, very little contained live vermin. The newly hatched larvae perish in a day and a half unless they can obtain food.

With regard to the head-louse:—

Ye ugly, creepin’, blastit wonner,

Detested, shunn’d by saunt an’ sinner,

it is smaller than the body-louse, and is of a cindery grey colour. The female measures 1·8 mm. in length and 0·7 in breadth. Like the body-louse, it varies its colour somewhat with the colour of the hair on the different branches of the human race. It lives amongst the hair of the head of people who neglect their heads; it is also, but more rarely, found amongst the eyelashes and in the beard. The egg, which has a certain beauty of symmetry, is cemented to the hair, and at the end of six days the larvae emerge, which, after a certain number of moults, become mature on the eighteenth day. The methods adopted by many natives of plastering their hair with coloured clay, or of anointing it with ointments, probably guards against the presence of these parasites. The Spartan youths, who used to oil their long locks before going into battle, may have feared this parasite. Some German soldiers, before going to war, shave their heads: thus they afford no nidus for P. capitis. The wigs worn in the late seventeenth and at the beginning of the eighteenth centuries undoubtedly owed something to the difficulty of keeping this particular kind of vermin down. The later powdering of the hair may have been due to the same cause.

This book, however, attempts to deal more with the troubles of the camp, and P. capitis is in war time less important than P. vestimenti. The former certainly causes a certain skin trouble, but the latter not only affords constant irritation, but, like most biting insects, from time to time conveys most serious diseases. P. vestimenti is said to be the carrier of typhus. This was, I believe, first demonstrated in Algeria, but was amply confirmed last year in Ireland, when a serious outbreak of this fever took place, though little was heard of it in England. Possibly, P. capitis also conveys typhus, but undoubtedly both convey certain forms of relapsing or recurrent fever. The irritation due to the body-louse weakens the host and prevents sleep, besides which there is a certain psychic disgust which causes many officers to fear lice more than they fear bullets. Lice are the constant accompaniment of all armies; and in the South African War as soon as a regiment halted they stripped to the skin, turned their clothes inside out, and picked the Anoplura off. As a private said to me: ‘We strips and we picks ’em off and places ’em in the sun, and it kind o’ breaks the little beggars’ ’earts!’

In conjunction with the Quick Professor of Biology at Cambridge, I have drawn up the following rules. None of them will be possible at all times, but some of them may be possible at some time in the campaign. At any rate, by acting on these rules, a relative of mine who took part in the South African War was able to escape the presence of lice on his body, and the General commanding his brigade told me on his return that he was the only officer—and in fact the only man—in the brigade who had so escaped.

How the Soldier may Guard Himself against Infestation with Lice

In times of war, when men are aggregated in large numbers and personal cleanliness—but especially an adequate change of clothing—cannot be secured, infestation with lice commonly takes place. The prevalence of lice in troops in the South African War was a source of serious trouble in that their attacks caused much irritation to the skin and disturbed men’s sleep.

Lice occur chiefly on the body (Pediculus vestimenti) and head (P. capitis). They are small greyish-white insects. The female lays about sixty eggs during two weeks; the eggs hatch after nine to ten days. The lice are small at first; they undergo several moults and grow in size, sucking blood every few hours, and attain sexual maturity in about two weeks. The eggs will not develop unless maintained at a temperature of 22° C. or over—such as prevails in clothing worn on the human body or in the hair of the head. This is why, when clothing is worn continuously, men are more prone to become infested with lice derived from habitually unclean persons, their clothing, bedding, &c. P. capitis lives between the hair in the head, and the eggs, called ‘nits,’ are attached to the hairs. P. vestimenti lives in the clothing, to which it usually remains attached when feeding on man; it lays its eggs in the clothing, and usually retreats into the seams and permanent folds therein. This is of importance in considering the means of destroying lice.

To avoid these pests the following rules should be observed:—

1. Search your person as often as possible for signs of the presence of lice—that is, their bites. As soon as these are found, lose no time in taking the measures noted under paragraph 5.

2. Try not to sleep where others, especially the unclean, have slept before. Consider this in choosing a camping-ground.

3. Change your clothing as often as practicable. After clothes have been discarded for a week the lice are usually dead of starvation. Change clothes at night if possible, and place your clothing away from that of others. Jolting of carts in transport aids in spreading the lice, which also become disseminated by crawling about from one kit to another. Infested clothing and blankets, until dealt with, should be kept apart as far as possible.

4. Verminous clothes for which there is no further use should be burnt, buried, or sunk in water.

5. If lice are found on the person, they may be readily destroyed by the application of either petrol, paraffin oil, turpentine, xylol, or benzine. Apply these to the head in the case of P. capitis. Remember that these fluids are all highly inflammable. When possible, soap and wash the head twenty-four hours after the last application of petrol, &c. The application may be repeated on two or more days if the infestation is heavy. Fine combs are useful in detecting and removing vermin from the head. Tobacco extract has been advocated failing other available remedies. In the case of P. vestimenti, the lice can be killed as follows: Under-clothes may be scalded—say, once in ten days. Turn coats, waistcoats, trousers, &c., inside out; examine beneath the folds at the seams and expose these places to as much heat as can be borne before a fire, against a boiler, or allow a jet of steam from a kettle or boiler to travel along the seams. The clothing will soon dry. If available, a hot flat-iron, or any piece of heated metal, may be used to kill vermin in clothing. Petrol or paraffin will also kill nits and lice in clothing. If no other means are available, turn the clothing inside out, beat it vigorously, remove and kill the vermin by hand—this will, at any rate, mitigate the evil.

6. As far as possible avoid scratching the irritated part.

7. Privates would benefit by instruction in these matters.

8. Apart from the physical discomfort and loss of sleep caused by the attacks of lice, it should be noted that they have been shown to be the carriers of typhus and relapsing fever from infected to healthy persons. Typhus, especially, has played havoc in the past, and has been a dread accompaniment of war.

Dr. R. F. Drummond has drawn my attention to a common folklore belief emplanted in the minds of our poorer people. Incredible as it seems, these uneducated and ignorant folk believe that lice on the person is a sign of productivity, and that should they be removed their hosts will become barren or sterile. They transfer, by a process of sympathetic magic, the productivity of the lice to the lousy. As Dr. Drummond writes, these ignorant mothers and aunts believe that the nits and the lice arise spontaneously, and are ‘an outward and visible sign of an inward and invisible fertility.’ Those who try to cleanse the heads and the bodies of our primary schoolchildren are ‘up against’ the superstitions of the little ones’ guardians, and the guardians unfortunately often prove the stronger. Similar views are held widely by the various peoples of India and the East—people we call heathen—and, apart from the connexion thought to be established between fertility and lice, the presence of the latter is considered both at home and abroad to be a sign of robust health.

The rather obscure connexion of the louse and the pike (Esox lucius) is probably due to the fact that the Latin name for the pike is Lucius. The poor pun in ‘The Merry Wives of Windsor’ on the Lucy family is due to a similar resemblance in sound.

The Editor of the Morning Post has given me leave to quote the following paragraphs from an article by his able Correspondent at Petrograd.

All armies, after a few weeks’ campaigning, whatever other hardships may come their way, are sure of one—namely, certain parasites. Even officers under most favourable conditions are unable to keep clear of this scourge. Silk under-clothing is some palliative, but no real preventative. Various measures have been proposed to relieve the intense annoyance caused by millions of parasites of at least two species. Flowers of sulphur, worn in bags round the neck, were supposed to be a preventative, but proved fallacious.[1] What seems likely to prove perfect prophylactery is recommended by M. Agronom, who writes from Bokhara, where he has noted the habits of the Sarts and their preventative measures.

The Sarts never wash, and hardly ever in lifetime change their clothes; therefore their condition would be impossible without some preventative measures. They take a small quantity of mercury, which they bray into an amalgam with a plant used in the East for dyeing the hair and nails—probably henna. This paste is evenly laid on strands of flax or other fibres. One string thus prepared is worn round the neck and the other round the waist next the skin, the heat of the body producing exhalations which kill parasites. The string lasts quite a long time.

M. Agronom has made experiments with the ordinary mercurial ointment prepared with any kind of fat, and finds the effect precisely the same. He asserts that such a minute quantity of mercury as is required to produce the desired result is perfectly harmless to the system. A half-crown’s worth of mercury brayed in a mortar with lard or other fat will suffice to treat enough threads for several hundred soldiers. The threads should be of ten or a dozen strands or some very loosely twisted material like worsted, and should be wrapped in parchment paper before boxing for dispatch to the soldiers. This is effective and lasting for body parasites. Others are easily dealt with by rubbing in petroleum, which must be done twice at a week’s interval.

It should also be noted that no ordinary washing methods will clear the parasites from body-linen even when dipped in boiling water; but if a couple of spoonfuls of petroleum are added to every gallon of water, perfect success is assured even without boiling.

I confess I think he is a little bit too dogmatic about the habits of the Sarts. I am told the better-class Sarts do occasionally bathe, or why are there public baths at Khiva? After all, in our oldest and most cultured University, only a year ago, the venerable Head of a House exclaimed with some acerbity, when a junior Fellow suggested putting up hot-water baths for the undergraduates: ‘Baths! why the young men are only up eight weeks!’

And, again, though the clothes of the Sarts are doubtless flowing, unless they are elastic, they must get bigger as babyhood passes to boyhood and boyhood passes to manhood.

Preparations of mercury are also used in India: not only against human lice, but against the Mallophaga or biting-lice which infest the Indian birds used in falconry. It is difficult for a zoologist to believe the last paragraph of the Morning Post correspondent. The temperature of boiling water coagulates animal protoplasm as it does that of the white-of-egg; and what would the lice do then, poor things?

Early in the year, Mr. C. P. Lounsbury, the well-known Government Entomologist in South Africa, wrote that they were supplying the troops there with sulphur-bags which were supposed to keep the lice away. The sulphur is put in small bags of thin calico, and several of these are secured on the under-clothing, next to the skin. The bags are about two inches square, and I am told that it is customary to have one worn on the trunk of the body and one against each of the nether limbs. Whether this is effective will probably be known soon; but that flowers of sulphur do play an effective part in keeping down these troubles is shown by a letter of Dr. Harding H. Tomkins:—

Over thirty years ago, when house-surgeon at the Children’s Infirmary, Liverpool, I used this with absolute success in all cases of plaster-of-Paris jackets who formerly had been much distressed by vermin getting under the jacket. The sulphur was rubbed well into the under-clothes.

But still more interesting evidence is given by Dr. N. Bishop Harman:—

When I was serving in the South African War, and attached to No. 2 General Hospital at Pretoria, I was detailed to take medical charge of the camp of released prisoners that was established a few miles out of the town on the Delagoa Bay railway line. I moved into the camp the night they came in. Next day an inspection was held. I do not think I ever saw such a sorry sight. The men were in the most nondescript garments, and they were flabby from the effects of the food the Boers had given them—mealy pap, for the most part. They had had no washing facilities, and they were dirty in the extreme. Amongst them were a number of men of the D.C.O. Yeomanry, many of them Cambridge men, and when these came to me for special examination, unwarily I invited them into my tent to strip, and their clothes were laid on the only available support—my bed. The next day or two was spent in cleaning up the men and refitting them. By the end of the week I noticed in the evening an unpleasant itch about the lower part of the trunk: a sub-acute sort of itch, it did not seem like a flea, and I could find nothing. But after a most diligent search with all the candles I could borrow, I found, to my horror, a louse. It was a genuine body-louse. Then I remembered my folly in inviting strangers into my tent. Water was scarce, the morning tub was only the splash from a can. Laundry was impossible. But after some trouble I managed to get a can of hot water and get some sort of a hot wash. My man did the best he could with my shirt and pants. What to do with the bedding—dark brown blankets—I did not know, except to expose them to the hot sunshine. I rode into the town, but insect-powder could not be got. It came into my mind that I had read or heard that people who took sulphur-tablets smelled of H₂S, so on the chance that an outside application might be of some service I got a supply of flowers of sulphur. This I liberally sprinkled all over my clothes, bedding, and rubbed into the seams of my tunic and riding-breeches. The itching was stopped in a day, and it never came again. But I soon noticed another circumstance: all the bright brass buttons of my tunic, although freshly polished by my man every morning, were tarnished before evening, even in the clean, dry atmosphere of the dry veld. Also my silver watch-case went black. There was no doubt that the sulphur was acted upon by the secretions of the skin and H₂S was produced, and this I had no doubt killed off any lice that could not be got at by washing. Subsequently, I always used it when I was in likely places. And some places were very likely! In Cape Town, I had to inspect all the soldiers’ lodgings in view of the spread of the plague. And, again, I had charge of a Boer prison-ship, and never once did I catch so much as a hopper. The prison-ship was literally alive with cockroaches of all sizes; our cabins swarmed with them, but they avoided my clothes and kit like a plague, and there was never a nibble-mark to be found. I gave the hint to many men and they confirmed my experience. I have since met other men who hit on the same device with equal success. In this war I have told the tip to many friends, and some relatives, who have gone out, and so far they have been free from the plague. You will note that I used all the other measures I could, but my bedding and uniform were not washed, and the lice must have come through the bedding; there was no other possible means I could trace. Yet the flowers of sulphur killed off all that might be therein.

A very effective method for exterminating vermin in infected troops was carried out by Dr. S. Monckton Copeman, F.R.S., at Crowborough. To put the matter briefly, I append a copy of his able and concise memorandum which was distributed to all the medical officers of the Division; but further details may be obtained by referring to the British Medical Journal, or the Lancet of February 6, 1915.

To the Medical Officer....

Treatment for Destruction of Vermin.

Arrangements should be made for the bathing of affected individuals and other inmates of infected tents.

After drying themselves, men to lather their bodies with cresol-soap solution (water 10 galls., Jeyes’ fluid 1½ oz., soft soap 1½ lb.), especially over hairy parts, and to allow the lather to dry on.

Shirts to be washed in cresol-soap solution made with boiling water.

Tunics and trousers to be turned inside out, and rubbed with same lather, especially along the seams. Lather to be allowed to dry on the garment.

The materials can be obtained from the A.S.C. on indent authorised by A.D.M.S. in the form attached.

Infected blankets were at first treated by soaking them in cresol-soap solution, after which they were sent to a neighbouring laundry to be washed—a small contract rate having previously arranged. In the first week in November, however, a portable Thresh’s steam disinfecting apparatus was supplied to the Division, through the Second Army, since when no difficulty has been experienced in the disinfection both of clothing and blankets.

As a matter of fact the simple and inexpensive method which has been employed by us over a period of several months has proved so successful that no necessity has arisen for a trial of any other means of treatment.

Professor Lefroy, of the Royal College of Science and Technology, recommends two effective remedies, known respectively as ‘Vermijelli’ and ‘Vermin Westropol.’[2] Lieut.-Colonel E. J. Cross has successfully treated the clothes and bedding of his men with a powder consisting of three parts of black hellebore root and one of borax, and many similar powders are produced by the manufacturers of insecticides.

Let us end up this chapter cheerfully!

The importance of lice is equalled by their unpopularity. A lady, driven to extremes by—well let us call it—the want of gallantry of Dr. Johnson, called him ‘a louse.’ The great lexicographer retorted, ‘People always talk of things that run in their heads!’

CHAPTER II

THE BED-BUG (Cimex lectularius)

In ‘x’ finita tria sunt animalia dira;

Sunt pulices fortes, cimices, culicumque cohortes;

Sed pulices saltu fugiunt, culicesque volatu,

Et cimices pravi nequeunt foetore necari.

(Anon.)

Among the numerous disagreeable features of the bed-bug is the fact that it has at least two scientific names—Cimex (under which name it was known to the classical writers) and Acanthia. The latter name is favoured by French and some German authorities, but Cimex was the name adopted by Linnaeus, and is mostly used by British writers, and will be used throughout this article. One cannot do better than take the advice of that wise old entomologist, Dr. David Sharp, and allow the name ‘Acanthia to fall into disuse.’

The species which is the best known in England is C. lectularius; but there is a second species which is much commoner in warm climates, C. rotundatus. As regards carrying disease, this latter species is even more dangerous than its more temperate relative. Other species, which rarely if ever attack man, are found in pigeon-houses and dove-cotes, martins’ nests, poultry-houses, and the homes of bats.

Fig. 3.—Cimex lectularius, male. × 15. (From Brumpt.)

The common bed-bug seems to have arrived in England about the same time as the cockroach—that is, over four hundred years ago, early in King Henry VIII’s reign. Apparently, it came from the East, and was for many years confined to seaports and harbours. It seems to have been first mentioned by playwriters towards the beginning of the seventeenth century. The sixteenth-century dramatists could never have resisted mentioning the bug had it been in their time a common household pest. It would have appealed to their sense of humour.

How the insect got the name of ‘bug’ is unknown. It has been suggested that the Old English word ‘bug,’ meaning a ghost or phantom which walked by night, has been transferred to Cimex. This may be so, but the ‘Oxford English Dictionary’ tells us that proof is lacking.

The insect is some 5 mm. in length and about 3 mm. in breadth, and is of a reddish- or brownish-rusty colour, fading into black. Its body is extraordinarily flattened, so that it can readily pass into chinks or between splits in furniture and boarding, and this it does whenever daylight appears, for the bug loves darkness rather than light. The head is large, and ends in a long, piercing, four-jointed proboscis, which forms a tube with four piercing stylets in it. As a rule the proboscis is folded back into a groove, which reaches to the first pair of legs on the under surface of the thorax. This folding back of the proboscis gives the insect a demure and even a devout expression: it appears to be engaged in prayer, but a bug never prays. The head bears two black eyes and two four-jointed antennae. Each of the six legs is provided with two claws, and all the body is covered with fairly numerous hairs. The abdomen shows seven visible segments and a terminal piece.

The bug has no fixed period of the year for breeding; as long as the temperature is favourable and the food abundant, generation will succeed generation without pause. Should, however, the weather turn cold the insects become numbed and their vitality and power of reproduction are interrupted until a sufficient degree of warmth returns.

Like the cockroach, the bed-bug is a frequenter of human habitations, but only of such as have reached a certain stage of comfort. It is said to be comparatively rare in the homes of savages, but it is only too common in the poorer quarters of our great cities. Its presence does not necessarily indicate neglect or want of cleanliness. It is apt to get into trunks and luggage, and in this way may be conveyed even into the best-kept homes. It is also very migratory and will pass readily from one house to another, and when an infested dwelling is vacated these insects usually leave it for better company and better quarters. Their food-supply being withdrawn, they make their way along gutters, water-pipes, &c., into adjoining and inhabited houses. Cimex is particularly common in ships—especially emigrant ships—and, although unknown to the aboriginal Indians of North America, it probably entered that continent with the ‘best families’ in the Mayflower.

Perhaps the most disagreeable feature of the bed-bug is that it produces an oily fluid which has a quite intolerable odour; the glands secreting this fluid are situated in various parts of the body. The presence of such glands in free-living Hemipterous insects is undoubtedly a protection—birds will not touch them. One, however, fails to see the use of this property in the bed-bug. At any rate, it does not deter cockroaches and ants, as well as other insects, from devouring the Cimex. There is a small black ant in Portugal which is said to clear a house of these pests in a few days, but one cannot always command the services of this small black ant.

Another remarkable feature is that the insect has no wings, although in all probability its ancestors possessed these useful appendages. As the American poet says:—

The Lightning-bug has wings of gold,

The June-bug wings of flame,

The Bed-bug has no wings at all,

But it gets there all the same!

The power of ‘getting there’ is truly remarkable. Man, their chief victim, has always warred against bugs, yet, like the poor, bugs ‘are always with us.’ I heard it stated, when I was living in southern Italy, that if you submerged the legs of your bed in metal saucers full of water and placed the bed in the centre of the room, the bugs will crawl up the wall, walk along the ceiling and drop on to the bed and on to you. Anyhow, whether this be so or not, there is no doubt that these insects have a certain success in the struggle for life, and only the most systematic and rigorous measures are capable of ridding a dwelling of their presence.

Fig. 4.—Egg of Cimex lectularius. Enlarged. (After Marlatt.)

The eggs of the bed-bug are pearly white, oval objects, perhaps 1 mm. in length. At one end there is a small cap surrounded by a projecting rim, and it is by pushing off this cap, and through the orifice thus opened, that the young bug makes its way into the outer world after an incubation period of a week or ten days. There is no metamorphosis—no caterpillar and no chrysalis stages. The young hatch out, in structure miniatures of their parents, but in colour they are yellowish-white and nearly transparent. The young feed readily, and feeding takes place between each moult, and the moults are five in number, before the adult imago emerges. This it does about the eleventh or twelfth week after hatching. These time-limits depend, however, upon the temperature after hatching, and the rate of growth depends not only upon the temperature but also upon the amount of food.

When bred artificially and under good conditions, the rate of progress can be ‘speeded up’ so that the eggs hatch out in eight days, and every following moult takes place at intervals of eight days, so that the period from egg to adult can be run through in as short a time as seven weeks.

Fig. 5.—Newly hatched young of Cimex lectularius. 1, Ventral view; 2, dorsal view. Enlarged. (After Marlatt.)

Unless fed after each moult, the following moult is indefinitely postponed. Hence it follows that in the preliminary stages bugs must bite their hosts five times before the adult form emerges, and the adult must, further, have a meal before it lays its eggs. The eggs are deposited in batches of from five to fifty in cracks and crevices, into which the insects have retired for concealment.

Bugs can, however, live a very long time without a meal. Cases are recorded in which they have been kept alive for more than a year incarcerated in a pill-box. When the pill-box was ultimately opened, the bugs appeared to be as thin as oiled paper and almost so transparent that you could read The Times[3] through them; but even under these conditions they had managed to produce offspring. De Geer kept several alive in a sealed bottle for more than a year. This power of existing without food may explain the fact that vacated houses occasionally swarm with bugs even when there have been no human beings in the neighbourhood for many months.

The effect of their bite varies in different people. As a rule, the actual bite lasts for two or three minutes before the insect is gorged, and at first it is painless. But very soon the bitten area begins to swell and to become red, and at times a regular eruption ensues. The irritation may be allayed by washing with menthol or ammonia. Some people seem immune to the irritation; and I know friends who, in the West Indian Islands, have slept through the attacks of thousands of bugs, and only awoke to their presence when in the morning they found their night-clothing and their sheets red with blood, expressed from the bodies of their tormentors as the victims turned from side to side.

As a rule, the uncovered parts of the body—the face, the neck, and the hands—are said to be more bitten than the parts which are covered by the bedclothes. This is not, however, my experience.

The bug has been accused of conveying many diseases—typhus, tuberculosis, plague, and a form of recurrent fever produced by a spirochaete (Spirochaeta obermeieri); but a critical examination throws some doubt upon the justice of the accusation, and Professor C. J. Martin writes as follows:—

There is really no evidence to incriminate the bed-bug in the case of either typhus or relapsing fever. It is possible to transmit plague experimentally by means of bugs, but there is no epidemiological reason for supposing this takes place to any extent in nature.

There are two differences in the habits of bugs and those of fleas and lice which may possess epidemiological significance. The first concerns the customary intervals between their meals. Bugs show no disposition to feed for a day or two after a full meal, whereas fleas and lice will suck blood several times during the twenty-four hours. The second is in respect to the time the insects retain a meal and the extent to which it is digested before being excreted. Fleas and lice, if constantly fed, freely empty their alimentary canals, and the nature of their faeces indicates that the blood has undergone but little digestion.

Both these insects evacuate such undigested or half-digested blood per rectum during the act of feeding, and the remnants of the previous meal are thus deposited in the immediate vicinity of a fresh puncture. It is not unlikely that, should the alimentary canal of the insect be infected with plague bacilli, spirochaete, or the organism responsible for typhus fever, these may be inoculated by rubbing or scratching. Bugs have not this habit; and in all the cases I have examined their dejections were fully digested, almost free from protein, and consisted mostly of alkaline haematin.

Whether bugs be guilty of these crimes or not, they are the cause of an intense inconvenience and disgust, and should, if possible, be dealt with drastically. At the present time[4] there are rumours that some of our largest camps are infested with these insects, and there seems no doubt that some of the prisoners and refugees to this country have brought their fauna with them, and this fauna is very capable of spreading in concentration camps. The erection of wooden huts—no doubt a pressing necessity—will afford convenient quarters for these pests.

Among the measures which have been most successful in the past has been fumigating houses with hydrocyanic-acid gas; but this is a process involving considerable danger, and should only be carried out by competent people under the most rigorous conditions. In all fumigating experiments every crack and cranny of a house should be shut, windows closed, keyholes blocked, and so on. A second method of fumigation is that of burning sulphur. Four ounces of brimstone are set alight in a saucer, this in its turn is placed in a larger vessel, which protects the floor of the room from a possible overflow of the burning material. After all apertures have been successfully plugged, four or five hours of the sulphurous fumes are said to be sufficient to kill the bugs, but to ensure complete success a longer time is needed. This is not only a much less expensive but a much less dangerous operation than using hydrocyanic-acid gas. Two pounds of sulphur will suffice for each thousand cubic feet of space, but it is well to leave the building closed for some twenty-four hours after the fumigation. Another more localised method of destroying these pests is the liberal application of benzine, kerosene, or any other petroleum oil. These must be introduced into all crevices or cracks by small brushes or feathers, or injected with syringes. In the same way oil of turpentine or corrosive-sublimate has proved effective. Boiling water is also very fatal when it can be used; and recently in the poorer quarters of London the ‘flares’ which painters use in burning off paint have proved of great use in ridding matchboarding, or wainscoting, from the harbouring bugs. Passed quickly along, the flame of the ‘flare’ does not burn the wood, but it produces a temperature which is fatal to the bug and to its young and to its eggs. And thus:—

‘This painted child of dirt, that stinks and stings’[5] is destroyed.

CHAPTER III

THE FLEA (Pulex irritans)

Marke but this flea, and marke in this,

How little that which thou denyst me is;

It sucked me first, and now sucks thee,

And in this flea our two bloods mingled bee.

(Dr. Donne.)

The fact, now fully established, that the bubonic plague is conveyed to man from infected rats, or from infected men to healthy men, by fleas has taken that wingless insect out of the category of those animals which it is indelicate to discuss.

No doubt, as Mr. Dombey says, ‘Nature is on the whole a very respectable institution’; but there are times when she presents herself in a form not to be talked about, and until a few years ago the flea was such a form. Hence, few but specialists have any clear idea either of the structure or of the life-history or of the habits—save one—of the flea.

Fig. 6.—Pulex irritans, female. The legs of the left side only are shown. Enlarged. (After a drawing by A. Dampf.)

Fleas are temporarily parasitic on many mammals and birds, but some mammals and some birds are much freer from fleas than others. As the flea is only on its host for part of the time, it has to put in the rest of its existence in some other place, and this, in the case of the human flea, is usually the floor, and in the case of bird-fleas the nest; from these habitats they can easily regain their hosts when the latter retire to rest. But large numbers of Ungulates—deer, cattle, antelopes, goats, wild boars—sleep in different places each recurrent night, and to this is probably due the fact that, with the exception of two rare species—one taken in Northern China and the other in Transcaucasia—the Ungulates have furnished descriptive science with no fleas at all. Both of these Ungulate fleas are allied to the burrowing-fleas or ‘chigoes.’

I know none of my readers will believe me when I say that the same is true of monkeys; but I do this on the undoubted authority of Mr. Harold Russell, who has recently published a charming little monograph on these lively little creatures. Monkeys in nature are cleanly in their habits; and although in confinement occasionally a human flea attacks them, and although occasionally a chigo bores into the toes of a gorilla or chimpanzee, ‘speaking generally, it may be said that no fleas have been found truly parasitic on monkeys.’ Whatever the monkeys are looking for, it is not fleas. What they seek and find is in effect little scabs of scurf which are made palatable to their taste by a certain sour sweat.

As a rule, each host has its own species of flea; but though for the most part Pulex irritans is confined to man it is occasionally found on cats and dogs, whilst conversely the cat- and dog-fleas (Ctenocephalus felis and Ct. canis) from time to time attack man.

The bite of the flea is accompanied by the injection of the secretions of the so-called salivary glands of the insect, and this secretion retards the coagulation of the victim’s blood, stimulates the blood-flow, and sets up the irritation we have all felt.

It is only a few years ago that the spread of bubonic plague was associated first with rats, and then with rat-fleas; and at once it became of enormous importance to know which of the numerous species of rat-flea would attack human beings. The Hon. Charles Rothschild, who has accumulated a most splendid collection of preserved fleas in the museum at Tring, had some years ago differentiated from an undifferentiated assemblage of fleas a species first collected in Egypt, but now known to be the commonest rat-flea in all tropical and sub-tropical countries. This species Xenopsylla cheopis—and to a lesser extent Ceratophyllus fasciatus—unfortunately infests and bites man. If they should have fed upon a plague-infected rat and subsequently bite man, their bites communicate bubonic plague to human beings. Plague—the Old English ‘Black Death’—is a real peril in our armies now operating in Asia and in certain parts of Africa.

Just as some fleas attack one species of mammal or bird and avoid closely allied species, so the human flea has its favourites and its aversions. There is a Turkish proverb which says ‘an Englishman will burn a bed to catch a flea,’ and those who suffer severely from fleabites would certainly do so. The courage of the Turk in facing the flea, and even worse dangers, may be, as the schoolboy wrote, ‘explained by the fact that a man with more than one wife is more willing to face death than if he had only one.’ But there are persons even a flea will not bite. Mr. Russell has reminded us in his Preface of the distinguished French lady who remarked, ‘Quant à moi ce n’est pas la morsure, c’est la promenade!’

Fig. 7.—Larva of Pulex irritans. C.f. frontal horn; d, antenna. Enlarged. (After Brumpt.)

There are one or two structural features in a flea which are peculiar: the most remarkable being that, unlike most other insects, it is much taller than it is broad. As a rule, insects—such as a cockroach, the bed-bug, or a stag-beetle—are like skates, broader than they are thick, but the flea has a laterally compressed shape, like a mackerel or a herring. Then, again, the three segments or rings which come after the head are not fused into a solid cuirass or thorax as they are in the fly or the bee, but they are movable one on the other. Finally, it is usual in insects for the first joint of the leg to be pressed up against and fused with those segments of the body that bear them; but in the flea not only is this joint quite free, but the body-segment gives off a projection which stretches out to bear the leg. Thus the legs seem, unless carefully studied, to have an extra joint and to be—as indeed it is—of unusual length. They certainly possess unusual powers of jumping—as Gascoigne, a sixteenth-century poet (1540–78) writes, ‘The hungry fleas which frisk so fresh.’

The male, as is so often the case amongst the Invertebrata, is much smaller than the female. The latter lays at a time from one to five minute, sticky, white eggs, one-fortieth of an inch long by one-sixtieth broad. They are not laid on the host, but in crevices between boards, on the floor, between cracks in the wainscoting, or at the bottom of a dog-kennel or in birds’ nests. Mr. Butler recalls the case of a gentleman who collected on four successive mornings sixty-two, seventy-eight, sixty-seven, and seventy-seven cat-fleas’ eggs from the cloth his cat had slept upon. Altogether 284 eggs in four nights! The date of hatching varies very much with the temperature. Pulex irritans takes half as long again—six weeks instead of four—to become an adult imago in winter than it does in summer. But in India the dog-flea will complete its cycle in a fortnight.

Fig. 8.—Pupa of flea. (After Westwood.)

When it does emerge from the egg the larva is seen to be a whitish segmented little grub without any limbs, but with plenty of bristles which help it to move about; this it does very actively. There are two small antennae and a pair of powerful jaws, for the larva does not take liquid food, but eats any scraps of solid organic matter which it comes across: dead flies and gnats are readily devoured. The larva casts its skin several times, though exactly how often it moults seems still uncertain.

After about twelve days of larval existence it spins itself a little cocoon in some sheltered crevice, and turns into a whitish inert chrysalis or pupa. During its pupal existence it takes, of course, no food, but it grows gradually darker, and after undergoing a tremendous internal change, breaking down its old tissues and building up new ones, the chrysalis-case cracks and the adult flea jumps out into the world.

There are many superstitions about fleas. March 1st is in some way connected with them, and in the south of England the house-doors are in some villages closed on that day under the belief that this will render the building immune for the following twelve months. The most successful insecticide is said to be prepared from Pyrethrum, which is grown in the Near East in large quantities for this purpose. But the Austrians, the Serbians, and the Montenegrins are fighting over the chief world-supply of this plant—possibly without knowing what they are doing—and ‘Insektenpulver’ is bound to go up in price. Wormwood (Artemisia) is also recommended.

While wormwood hath seed, get a handfull or twaine,

To save against March, to make flea to refraine;

When chambere is swept and wormwood is strowne,

No flea for his life dare abide to be known.

(Tusser.)

The author of ‘A Thousand Notable Things’ suggests the following plan, but, so far, I have not met anyone who has tried it: ‘If you mark where your right foot doth stand at the first time that you do hear the cuckow, and then grave or take up the earth under the same; wheresoever the same is sprinkled about, there will no fleas breed. I know it hath proved true.’

Plastering a floor with cow-dung is a common practice in South Africa, and seems to be an efficacious means of keeping down fleas. Dr. R. J. Drummond tells me that all natives of India and Ceylon spread an emulsion of cow-dung in hot-water over the floors and the walls of their dwellings to keep out fleas. This has been done from immemorial times, and is effective. The efficacy of the emulsion in keeping fleas away has been doubted, and so I am glad to quote a few lines from a kind letter sent me by Dr. P. A. Nightingale of Victoria, Southern Rhodesia, which put the matter in a happy light:—

I think the correct facts are these: the floors of certain houses, huts, &c., throughout the South African veld are made of ant-heap earth, moistened and beaten hard and flat with sticks. This floor is then smeared at regular intervals—say, every ten days—with fresh cow-dung, when the room becomes fresh and sweet (!) and free from insects.

However, before the smearing can be done it is necessary to turn all the furniture out of the room and to sweep it thoroughly; after the smearing, the doors and windows are left open for drying purposes.

Hence, I think that the absence of fleas in such quarters is really due to general cleanliness, sunlight, and fresh air, and not to any special virtue in the cow-dung.

I am, however, sure that the smearing of the floor at frequent intervals does keep many pests down by filling up, and temporarily sealing, the numerous cracks in the floor where fleas, &c., reside and breed in vast numbers.

Huts—especially unused ones—not smeared for many weeks contain (approximately) several thousands of fleas, white ants, centipedes, and scorpions to the square inch, when the only treatment is to cleanse the walls and floor with cyanide solution, or burn the whole place down.

Fig. 9.—Ceratophyllus gallinulae. Male (above) and female (below). Drawn to scale and both highly magnified. These specimens, taken from a grouse, are of the same genus as one of the plague-conveying fleas.

From long experience, I am very nearly insect proof; but cannot stand the myriads of fleas I occasionally have to sleep with in a hut of the above description—especially just before the rains set in, when additional veld pests come into the huts for shelter.

We must, in the long run, treat fleas seriously. Although the Pulex irritans is a very common insect, the greatest living authority on fleas tells me it has never been accurately drawn. We have Blake’s ‘ghost of a flea’; but what did Blake know of entomology? In distinguishing one flea from another—fleas which may attack man and fleas which have hitherto declined to do so—every hair, every bristle, counts. Hence, I illustrate this article with accurate outlines of certain fleas found on the grouse, and for whose accuracy I can vouch ([Fig. 9]).

As I have said above, a certain rat-flea (Xenopsylla cheopis) and another (Ceratophyllus fasciatus) undoubtedly convey the bacillus of plague from rats and other Murinae to man and vice versa. The Bacillus pestis is unlikely to establish itself in the present war in Europe, but Quién sabe? The Black Death of 1349–51 was conveyed by fleas, and so was Pepys’s Plague of 1665. Plague—flea-borne, we must remember—is still endemic in places as near Europe as Tripoli, and in numerous centres in Asia. Not a disease altogether to be neglected, since the spread of war to the Near East, but still not very threatening in Europe in the twentieth century.

CHAPTER IV

THE FLOUR-MOTH (Ephestia kühniella) IN SOLDIERS’ BISCUITS

Where moth ... doth corrupt. (Matt. vi. 19.)

It is not only those insects that destroy the continuity of our soldiers’ integument which play a part in war. It has been well said that an army marches on its stomach; and the admirable commissariat arrangements which have been so distinctive a feature of the British Expeditionary Force during the present war are the result of much patient care and attention during times of peace. I am in no position to discriminate, but I do believe that the admirable service of the A.S.C. and the R.A.M.C. is at least equal to the splendid record of those in the fighting-line.

Every one knows that recruits are frequently rejected for some defect in their teeth. A soldier, indeed, requires strong teeth, for his farinaceous food in the field is largely supplied to him in the form of biscuits—not that ‘moist and jovial sort of viand,’ as Charles Dickens described the Captain biscuit, but ‘hard-tack’ which challenges the stoutest molars.

During the summer of 1913 the authorities of the British Museum at South Kensington arranged a very interesting but somewhat gruesome exhibit in their Central Hall. The exhibit consisted mainly of Army biscuits eaten through and through by the larva of a small moth and covered by horrible webs or unwholesome-looking skeins of silky threads.

Fig. 10.—Ephestia kühniella. Moth-infested biscuit.

Together with these derelict biscuits were certain long metallic coils and other apparatus used in investigating certain phases of the life-history of the moth and the manufacture of the biscuit. The exhibit illustrates an article which had recently appeared on the Baking of Army Biscuits, by Mr. Durrant and Lieut.-Colonel Beveridge, on the ‘biscuit-moth’ (Ephestia kühniella), a member of the family Pyralidae. The article recorded their efforts to arrive at a means of checking this very serious pest to service stores.[6]

The biscuit-moth (E. kühniella) was described two years before its larva had been noted damaging flour at Halle. There has always been a certain amount of international courtesy in attributing the provenance of insect pests to other countries; and when E. kühniella began, about ten years later, to attract attention in England it was believed to have been introduced from the United States, via the Mediterranean ports, in American meal. The American origin was, however, denied by Professor Riley, who, in a letter to Miss Ormerod, states, ‘I think I can safely say that this species does not occur in the United States.’ At the moment of writing these words Professor Riley was in the act of packing-up to leave Washington for Paris. Possibly he was excited, certainly he was inaccurate, for the species was then known to be prevalent in Alabama, North Carolina, and other States. In fact, to-day it is recorded throughout Central America and the Southern States, and in most of the temperate regions of the New World.

Fig. 11.—Ephestia kühniella. × 2.

The moth itself is a rather insignificant, small insect, of a slatey-grey colour. Its eggs, rather irregular ovoids, are laid upon the biscuit into which the issuing larvae bore. These latter are soft and like most creatures which live in the dark, whitish, though with a tinge of pink; the head, however, is brown and hardened. The larva is constantly spinning silken webs or tissues, which in the most untidy way envelop the biscuit. It finally entombs itself in a whitish silken cocoon, and herein it ultimately turns into a chrysalis or pupa.

Another Pyralid moth—Corcyra cephalonica—makes similar unpleasant webs all over biscuits, rice, or almost any farinaceous food; but, since its larvae are unable to live unless there be a certain degree of moisture in its food, it is less injurious to baked food than the Ephestia, for whose larvae nothing can be too dry. Corcyra seems originally to be a pest of rice, and to have been introduced into Europe with Rangoon rice; but it readily alters its diet in new surroundings, and will live on almost any starchy stuff, if not too desiccated.

The problem that Lieut.-Colonel Beveridge and Mr. Durrant, of the British Museum, set out to solve was at what stage in the manufacture of the Army biscuits does our soldiers’ food become infested, and whether any steps could be taken to avoid or minimise such infestation.

Fig. 12.—Ephestia kühniella. A, Larva; B, pupa. Greatly magnified.

First, as to infestation. The biscuit must become infested either (1) at home before packing, (2) during transit, or (3) in the country where they are stored. The biscuits are packed in tins, hermetically sealed, and enclosed in wooden cases to prevent injury; it was therefore obvious that if insects could be found within intact tins it would be demonstrated at once that infestment must have taken place in the factories, and not subsequently.

Fig. 13.—Corcyra cephalonica. Moth-infested biscuit.

With a view to determine the origin of infestation sample tins were withdrawn from stocks at various stations abroad, and inspected by experts at Woolwich; and tins which, after careful examination, had been pronounced intact, were found to contain Ephestia kühniella and Corcyra cephalonica in various stages of development, thus proving conclusively that infestation had taken place in the factories before the tins were soldered, and indicating that preventive or remedial measures must be undertaken within the biscuit-making factories themselves.

It is obvious either that the heat to which the biscuit is subjected in the process of baking is insufficient to destroy any of the insect eggs present in the moist dough or that the moths and beetles deposit their eggs in or on the biscuits after baking, and during the process of cooling and of packing into the tins. Cooling before packing is necessary in order to allow the moisture in the centre of the biscuit to become evenly distributed throughout the ‘tissue’ of the biscuit. And it is during the time occupied in cooling and packing that the biscuit is exposed to the greatest risk of infestation; any risk occasioned by subsequent injury must be exceptional, and is probably negligible.

By a series of most ingenious experiments, the two investigators were able to determine the temperature in the centre of the biscuits during the various stages of its baking and cooling. Army biscuits are made from dough which contains about 25 per cent. of water. When stamped out they are placed in rows on the revolving floor of an oven, and are submitted to a high temperature for twenty minutes whilst they travel over a space of 40 feet. The dough at first contains, as we have said above, 25 per cent. of water, but during baking this is reduced to about 10 per cent., and the moisture now collects in the centre of the mass of the biscuit in consequence of the external hardening or ‘caramelisation,’ as it is called. The holes which are pricked in so many biscuits of course help to equalise the spread of the moisture throughout the biscuit.

Too little attention has been paid to the internal temperature of edibles which are being cooked. Very few people, for instance, have any conception of what is going on in the centre of a joint of meat whilst it is being roasted or boiled. After two hours’ boiling the temperature in the centre of a large ham has only risen to 35° C.; after six hours’ boiling to 65° C., and it is only after ten hours’ continuous boiling that 85° C. is reached. I have, I am sorry to say, no conception as to how long a ham ought to be boiled, but it is obvious that to be really effective against such parasites as Trichinella—the causa causans of trichinosis—the cooking of pork and ham should be more prolonged and thorough than seems to be customary. But that is another story.

However, to return to our biscuits. The Colonel and Mr. Durrant devised an ingenious instrument which determined the rising temperature at the centre of our Army biscuits whilst baking. When the tip of their recording apparatus lay within the moist area of the biscuit, the temperature registered was only a little over 100° C.; but when the tip of the instrument rested on the hard ‘caramelised’ portion much higher temperatures were observed—even as high as 125° C. Colonel Beveridge and Mr. Durrant were thus able to establish the fact that the temperatures of the biscuit were, during baking, such as to rule out the idea that the eggs of the biscuit-moth—which do not survive a temperature of 69° C. for twelve minutes—were deposited in the biscuit before cooking.

After the baking is completed the biscuits are cooled, and it is at this period that they are most exposed to risk of infestation by Ephestia kühniella. This insect is a well-known nuisance in Flour-mills. So persistent and numerous are these moths at times that they clog the rollers with their cocoons, and sometimes completely stop them. The webbing of the elevators in the mills gets covered with them and with their silky skeins, and then the elevators stop working. They mat together the flour and meal with their silken excreta, and so uniform is the temperature of the Mill, and so favourable to the life of the insect, that they complete their life-cycle in this country in two months, and in the warmer parts of America even more rapidly. In well-heated mills the proceeding is continuous, so that six generations at least may be produced each year.

The most efficient method of getting rid of this pest of the Army biscuit is a complete and thorough fumigation of the infested premises with carbon bisulphide. But, as this substance is not only poisonous but inflammable, it is well to get a chemist to undertake the proceeding, and also to notify the Insurance Company. Fumigation by sulphur ruins the flour. Another remedial measure is that of turning the steam from the boilers on to all the infected machinery and walls.

That this destruction of the Army biscuit is a matter of considerable importance is shown by the fact that biscuit-rations exported to the colonies in hermetically sealed tins have become quite unfit for consumption, and this destruction has been noted in places as far distant from each other as Gibraltar, the Sudan, Mauritius, Ceylon, South Africa, and Malta. That it is also an old trouble is shown by the following quotation from the diary which Sergeant Daniel Nicol, of the 92nd (the Gordon Highlanders), kept during the expedition to Egypt in 1801:—

Some vessels were dispatched to Macri Bay for bullocks, and others to Smyrna and Aleppo for bread which was furnished us by the Turks—a kind of hard dry husk. We were glad to get this, as we were then put on full rations, and our biscuits were bad and full of worms; many of our men could only eat them in the dark.[7]

With regard to the actual baking of the biscuit, Colonel Beveridge and Mr. Durrant suggest that the temperature conditions during the process of cooling should be made as unfavourable as possible for the moths by introducing screened cool air, which can be forced in at one end of the cooling-chamber and sucked out at the other. Could such a scheme be adopted it would be difficult, if not impossible, for the moths to lay their eggs, and the biscuit would thus be more rapidly cooled. In any case it should not be difficult to ensure that the cooling takes place in some chambers which are practically free from these destructive moths.

CHAPTER V

FLIES

Part I

THE HOUSE-FLY (Musca domestica)

Musca est meus pater, nil potest clam illum haberi;

Nec sacrum nec tam profanum quidquam est, quin Ibi ilico adsit.

(Plautus, Mercator.)

‘The common house-fly [says Ruskin] is the most perfectly free and republican of creatures. There is no courtesy in him; he does not care whether it is a king or clown whom he teases, and in every step of his swift mechanical march and in every pause of his resolute observation there is one and the same perfect expression of perfect egotism, perfect independence and self-confidence and conviction of the world having been made for flies. Your fly free in the air, free in the chamber, a black incarnation of caprice, wandering, investigating, fleeting, flitting, feasting at his will with rich variety of feast from the heaped sweets in the grocer’s window to those of the butcher’s back yard, and from the galled place on your horse’s neck to the brown spot on the road from which, as the hoof disturbs him, he rises with angry republican buzz; what freedom is like his?’

The house-fly is all that Ruskin describes it to be, but it is more. It is the most cosmopolitan of insects. Wherever man is there is the fly. It is found—

From Greenland’s icy mountains

To India’s coral strand.

But it is naturally more frequent in warm climates than in cold, as the rate of its development depends very largely upon an average high temperature.

Unlike the lice and the bed-bug, the fly like the flea, passes through a complete metamorphosis—egg, larva, pupa, and imago. It will breed in almost any rotten matter, whether vegetable or animal, and it breeds most successfully, as Gordon Hewitt has pointed out, when certain processes of organic fermentation are taking place in its breeding-place. Probably the fermentation has a favourable effect upon the food of the larvae. Undoubtedly the place most readily selected by the female for laying her eggs is stable-manure. A few years ago there was a remarkable reduction in the number of house-flies in London, and Lord Montagu of Beaulieu attributed this reduction to the refreshing and insecticidal petrol vapour with which the streets of that town were then bathed.

Fig. 14.—Mass of eggs of M. domestica. (From Gordon Hewitt.)

I do not know what experiments Lord Montagu had made on the subject of the insecticidal value of petrol vapour, but the ordinary man in the street attributed—and I think more correctly—the diminution of the plague of flies to the absence of the nidus in which the female fly lays her eggs. Stable-yards had been turned into garages. But flies will, indeed, breed in almost any kind of dejecta—including the human—and in rotten straw, rotten wool, cotton garments, decaying vegetables and fruits, bad meat, rotten grain, and even in spittoons, but they prefer horse-manure.

Fig. 15.—Eggs of M. domestica, × 40. (From Gordon Hewitt).

In our country house-flies usually begin to breed in June and July, continuing well on into October if the weather be but warm. Their greatest activity is, however, in the hotter month of August and the beginning of September. But in warm stables, restaurants, and kitchens flies are able to reproduce the whole year round. A single fly will deposit at one time 100 to 150 eggs, and in the course of her summer life may produce five, or even six, batches of ova of this size. The eggs are pearly white, elongated structures, with two converging lines, along which the egg-case will ultimately split to give exit to the larva. The eggs are laid, by means of a long ovipositor, a little way beneath the surface of the dung-heap in a position where they will not readily be dried up. In favourable conditions the eggs hatch in from eight to twenty-four hours.

The first larva is legless, tapering towards the head, which bears a pair of breathing-holes, or spiracles; the body is much stouter towards the hinder end. On the whole it is a white, unpleasant-looking maggot, called by freshwater-fishermen a ‘gentle.’ By contracting and expanding its body it pushes its way through the moist, semi-liquid surroundings. The skin is usually moulted some twenty-four hours after birth, but all these time-limits depend much upon the temperature and favourable conditions. With normally high temperatures—say, with 30° C. to 35° C.—the larva will become fully grown in five or six days. The third and final larval stage, after the second moult or ecdysis, lasts three days, and when fully grown the maggot is now about half an inch in length. Externally, twelve segments are visible, but the internal anatomy shows that thirteen are really present, though one is almost ‘masked.’

Fig. 16.—Abdomen of female house-fly, show­ing the extended ovi­positor. (From Gordon Hewitt.)

It is only during these larval stages that the insect grows, and it is never more bulky than in the third larval stage. Now it leaves the moist situation, in which it has flourished, and, crawling through the manure, seeks some dry or sheltered corner. For a time it rests, and then after an hour or two’s quiescence it retracts its anterior end and assumes a barrel-shaped outline, its creamy white colour slowly changing to a mahogany brown. The larval skin forms the pupa-case, and within this pupa-case the body of the larva undergoes a wonderful change, far greater than even human beings undergo at the time of puberty. Many of its organs are disintegrated and re-formed, and in the course of three or four days the white, legless, repellent maggot, who ‘loves darkness rather than light,’ is changed into a lively, flying insect, seeking ‘a place in the sun’ and the companionship of man. As the Frenchman said of the pig which goes into one end of the machine in the Chicago meat-factory as live pig and comes out at the other end in the form of sausages, ‘Il est diablement changé en route.’

Fig. 17.—Mature larva of M. domestica. a.sp, Anterior spiracular process; an.l, anal lobe; sp, spiniferous pad. I-XIII, Body segments. (From Gordon Hewitt.)

In a very short time after leaving the pupa-case the adult fly has stretched her wings, the chitin of her body has hardened, and she flies away ‘on her several occasions.’

Fig. 18.—‘Nymph’ of M. domestica dissected out of pupal-case about thirty hours after pupation. an, Swellings of nymphal sheath marking bases of antennae; cx, coxa of leg; lb, labial portion of proboscis sheath; lbr, labral portion of same; n.sp, spiracular process of nymph; w, wing in nymphal alar sheath. (From Gordon Hewitt.)

Fig. 19.—Pupal-case or puparium of M. domestica from which the imago has emerged, thus lifting off the anterior end or ‘cap’ of the pupa; ventro-lateral aspect. a.sp, Remains of the anterior spiracular process of larva; l.tr, remains of the larval lateral tracheal trunk; n.sp, temporary spiracular process of nymph; p.sp, remains of the posterior spiracles of larva. (From Gordon Hewitt.)

Flies become sexually mature in a week or ten days after emerging from the chrysalis-case, and are capable of depositing their eggs four days after mating, so that if the conditions be indeed favourable the whole development from the egg to the perfect fly may be accomplished in nine or ten days, and the second generations are able to lay their eggs ten days later. The appalling fecundity of such an insect explains the fact that in the hotter parts of the world nearly every edible thing seems to be covered with them.

The proboscis of a fly can only suck up liquid food; and when we see it feeding on solid substances, such as sugar, it has really dissolved the sugar by depositing some saliva on it, and is sucking up the sugary solution so produced. It not infrequently regurgitates its food in a spherical drop, which it generally re-absorbs.

As we have seen, flies are very susceptible to temperature, and with the approach of cold weather they seem to die. We used to think that some, in a state suspended animation, ‘carried on’ through the winter months. This is, however, ‘non-proven.’ Many of them undoubtedly die in the autumn, as bees die, of old age. They are literally worn out. But a great number fall victims to a parasitic fungus called Empusa. Flies killed by this fungus are frequently to be seen in autumn, hanging dead on windows, &c., surrounded by a little whitish powdery ring of spores formed by the fungus.

Flies, like many other insects, are extremely difficult to keep alive in captivity, and few have succeeded in rearing them for more than a month or two. At one time, as we have said, it was thought that those flies which survive the winter were fertilised females of the younger broods, and that during the winter they subsisted on their ‘fat bodies.’

Fig. 20.—M. domestica in the act of regurgitating food. × 4½. (From Gordon Hewitt.)

Doubt has recently been thrown on this theory, and in a recent report[8] of the Local Government Board Dr. Newsholme sets forth the results of the researches of Dr. Monckton Copeman and Mr. E. E. Austen in the following words:—

Until recently there was general agreement that a certain number of flies managed to survive the winter and spring by hibernating in dark nooks and crannies in dwelling-houses, or, as contended by Dr. Laver,[9] in various sheltered situations outside dwellings—such as the under-surface of the thatch of farmyard stacks. The researches of Mr. Jepson and others have shown that, during the period extending from late autumn to early summer, flies may be found occasionally in all active conditions in warmed houses, and especially in such places as kitchens and bake-houses, where the temperature is kept relatively high; and further, that under these conditions, and in presence of sufficient food material they may even continue to breed. Doubt has, however, been expressed as to whether a sufficient number of flies remain in active condition in these localities to perpetuate the species and to start the rapidly multiplying generations of the following summer. As to whether flies can persist through the winter in other than adult form practically nothing is known.

In view of the importance of obtaining further information on these points, some inquiries were undertaken into the hibernation of flies, the results of which were set out in a communication by Dr. Copeman published in the sixth report of this series. Arrangements were made with a working naturalist for the collection of any flies that could be found in situations like those which Dr. Laver and other observers had found to be favourite winter quarters of hibernating flies. In view of the need, pointed out by Howard, for expert identification of the species of all flies captured in a dormant condition during the winter months, the co-operation of Mr. Austen of the British Museum (Natural History) was obtained, and to him all the flies collected were submitted for examination. The one specially interesting and unexpected point emerging from this inquiry was that not a single specimen of the house-fly (Musca domestica) was met with among the considerable number of hibernating flies caught in situations which have hitherto been regarded as the special habit of this fly. Under these circumstances it was felt that further detailed investigation of the matter was needed; and, accordingly, inquiry on a more extended scale, and covering—as it proved—an extensive area, was initiated and carried through during the past winter.

*   *   *   *   *

Once more, the results obtained afford no support to the belief that house-flies hibernate, in this country, in the adult state; and the problem as to the manner in which the interval between one fly-season and the next is bridged over still remains unsolved.

Gordon Hewitt, Copeman, Howlett, Merriman,[10] and others, have made experiments as to how far a fly can travel. Marked flies have been taken within forty-eight hours at distances ranging from 300 yards to a mile. Apparently the direction of the wind plays a considerable part in the distance they travel.

The importance of the house-fly as a carrier of disease, especially bacterial disease, has recently been recognised especially in times of war. Moses was as great as a Principal Medical Officer as he was as a Director of Supplies; and this is shown in Deuteronomy, chapter xxiii, where he deals with the need of strict hygiene in the camp.

In the middle of the last century already attention was being drawn to the fact that the house-fly and the blow-fly transmitted various diseases. But it was during the Spanish-American War and the South African War which followed shortly afterwards that the part played by these pests in conveying enteric became definitely established. Flies coming straight from the latrines, with their legs and their wings and their proboscides soiled with typhoid bacilli, would enter the camp and the tents of the soldiers and settle on their food-supplies—crawling over their jam, floating in their milk. Thirty per cent. of the deaths in our South African War were due to typhoid fever. The bacillus, as is well known, is capable of existing for a long time and of persisting alive in the alimentary canal of the insect. Dr. Graham-Smith has shown that the bacilli may remain active for six days after feeding, and that the feet of flies which have the bacillus on them are capable of infecting surfaces upon which they walk for at least two days after first coming in contact with the germs that cause ‘enteric.’

Fig. 21.—A, Foot of a fly, showing hairs bearing bacteria; B, a single hair more highly magnified; C and C´, bacteria. Diagrammatic.

Faichne reared maggots in dejecta infected with typhoid bacilli, and he was able to show that the flies into which these maggots turned contained virulent typhoid germs in their intestines. There is absolutely no doubt that typhoid is largely conveyed by the agency of these insects; and as flies are perfectly controllable, if ‘the people will but have it so,’ it is one of the disgraces of our civilisation that this disease should be so prevalent.

The protective inoculation against enteric is now almost perfect, and its value is shown by quotations from a leaflet issued by the Research Defence Society:—

Sir William Leishman, in a letter published during the present war, August 22, 1914, says: ‘The benefits of inoculation are so well recognised in the regular forces that we find little difficulty, in foreign stations, in securing volunteers for inoculation: for instance, about 93 per cent. of the British garrison of India have been protected by inoculation; and typhoid fever, which used to cost us from 300 to 600 deaths annually, was last year responsible for less than 20 deaths. Inoculation was made compulsory in the American army in 1911, and has practically abolished the disease; in 1913 there were only 3 cases, and no deaths in the entire army of over 90,000 men.’

In Avignon, in the south of France, during the summer of 1912, typhoid fever broke out in the barracks. Of 2053 men, 1366 were protected and 687 were not. The non-protected had 155 cases of typhoid, of whom 21 died; the protected had not one case. In the winter of 1913 the French Senate resolved that the protective treatment should be made compulsory throughout the French army; and, in special circumstances, among the reservists.

Fig. 22.—Chart illustrating the relation of the numerical abundance of house-flies to summer diarrhoea in the city of Manchester in 1904. Prepared from statistics and chart given by Niven. (From Gordon Hewitt.)

Infantile diarrhoea, which so afflicts the crowded, poorer quarters of our cities in the summer, is another disease intimately associated with Musca domestica. But that is hardly a disease likely to trouble the soldiers. The tubercle bacillus is another germ conveyed by flies. House-flies are particularly fond of feeding on saliva; and Hayward, Lord, and Graham-Smith have obtained virulent bacilli from the intestines and dejecta of flies which had been fed on tubes containing tuberculous sputum. These experiments have been amply confirmed by other workers. Anyone who has ever been in Egypt will remember the terrible sight of the flies attacking little children suffering from ophthalmia and it is believed that the wide prevalence of this most pitiful trouble is attributable to the abundance of flies—the flies of Egypt, a plague even in the times of the Pharaohs. Things do not alter much in Egypt, and the Biblical plagues are wont to recur.

Another disease—anthrax, or wool-sorter’s disease—may be conveyed by the same carriers from infected cattle to man, and there is a good deal of epidemiological and bacteriological evidence available to show that flies play an important part in the spread of cholera, which is now threatening the soldiers in the eastern seat of the war, and possibly in disseminating the organisms which cause yaws and tropical sore.

It will be noticed that the fly is not a necessary second host for any of these germs. They are conveyed, as if by an inoculating needle, by contact with the proboscis or the legs or some other tainted organ of the fly. The bacilli, however, pass through the alimentary canal apparently unchanged and unharmed, and are deposited either with the regurgitated food from the fly’s stomach ([Fig. 20]), or with the dejecta of the insect. There is no subcutaneous inoculation—such as takes place in the case of the mosquito when it conveys malaria, or in the case of the tsetse-fly when it conveys sleeping sickness—where the disease-causing organism is injected into the human body. The action of the fly is mechanical, but none the less efficient. The poisoning of the soldiers’ food-supply is its chief rôle in war.

CHAPTER VI

FLIES

Part II

THE BLUE-BOTTLE (Calliphora erythrocephala), AND OTHERS

Who fills our butchers’ shops with large blue flies?

(Rejected Addresses.)

But there are other flies: first amongst which may be mentioned Fannia canicularis and F. scalaris. These belong to the family known as Anthomyidae, and are distinguished from the house-fly by being smaller in size, and by many other small details in the imago stage hardly to be appreciated except by trained dipterologists. For a short time at the beginning of the summer, during part of May and June, specimens of F. canicularis are more abundant than M. domestica, and, when seen on the window-panes of our living-rooms, are apt to be thought, by the uninformed, to be young specimens of the latter. But, as has been said, flies, when they are once flies, do not grow; all the growing they do is done in the larval stage.

Fig. 23.—Latrine-fly, Fannia scalaris, male (× 3). Antenna. Head of female, dorsal view. Natural size, resting position. (From Graham-Smith.)

As the days lengthen the common house-fly becomes vastly more common than F. canicularis, the ‘lesser house-fly,’ and the latter now tend to aggregate in those rooms of our houses not devoted to cooking, and may frequently be noticed flying in a jerky and disconcerting manner around the chandeliers or bedposts in unfrequented living- or bed-rooms. The relative proportion of these two genera in full summer varies in different localities. Roughly speaking, out of 100 flies collected in a house there is something between 90 and 99 per cent. of M. domestica, but the numbers not only vary with locality, but with temperature.

On the other hand, there is a curious disproportion between the number of sexes found ‘at home’ in the lesser house-fly. For every 100 F. canicularis taken indoors seventy to seventy-five are males, the numbers being evened by an equal preponderance of females who have remained out of doors.

Fig. 24.—Larva of F. canicularis. (From Gordon Hewitt’s Report to Local Government Board, 1912.) Magnified.

The larva of Fannia is a flattened-looking grub with distinct segments, decorated by numerous feathery processes. It lives amongst decaying vegetation and fruit, and also amongst fermenting animal matter and dejecta. Sometimes it is found in rotting grass. As we shall see later, it frequently passes into the human alimentary canal. F. scalaris, usually known as the ‘latrine-fly,’ is even commoner than its congener, and the external structural differences are minute. As its name indicates, it is found as a rule breeding in human dejecta, and is, therefore, as a typhoid carrier, much more dangerous than F. canicularis. Its larva is also more commonly found in the human intestine.

Then there are two species of large flies known as blue-bottles or blow-flies—Calliphora erythrocephala and C. vomitoria. The former of these is the more common. The sides of its face are golden yellow, set with black hair; whereas in C. vomitoria the sides of the face are black, but the hair is golden. Both are handsome, sturdy-looking diptera, with bluish-black thoraces, and abdomens of a dark metallic gun-metal sort of colour.

Blow-flies deposit their eggs on fresh or decaying flesh, and this is one of the great sources of trouble to the officers of the Army Service Corps. But they are not content with killed flesh. They will lay their eggs on any living flesh which is exposed, or in sores or tumours, and here their larvae will thrive. Dr. Graham-Smith tells us he once found the exposed muscles of the broken leg of a living rabbit seething with a mass of small blow-fly larvae, which were nourishing themselves upon the living tissues.

Fig. 25.—Blow-fly or blue-bottle, Calliphora erythrocephala, female (× 3). Antenna. Male head, dorsal view. Side view of head. Natural size, resting position. (From Graham-Smith.)

The eggs of the blow-fly hatch out in from ten to twenty hours in normal British temperatures; the larval life, in its three stages, lasts from seven to eight and a half days; the pupa state lasts a fortnight, so that the total development extends a day or two over three weeks. The maggots are unusually voracious; and Linnaeus used to say that the progeny of three blow-flies will dispose of a dead horse as quickly as three lions.

C. erythrocephala is essentially an outdoor fly and enters houses only in search of a nidus on which to deposit its eggs. C. vomitoria resembles its congener in size and habits, but it is not so abundant. Occasionally its eggs have been known to be deposited in the nostrils of animals and men.

But there are:—