More Minor Horrors

Apropos de bottes.—(Reynard.)

Britain wants many materials in this war, and as long as our back door is open we are getting them. Petrol, rubber, zinc, copper, molybdenum, vanadium, thorium, nickel, saltpetre, wool, cotton, are all coming to us in greater—immeasurably greater—quantities than those in which they can filter through neutral countries into Germany. These things count. The shortage of leeches in Great Britain, on which I have already dwelt, is negligible, and is entirely over-balanced by the really serious shortage of sausage-skins in middle Europe. I am told that our meat-salesmen at Smithfield were offered an incredible advance on the normal rate for these products—so-very-necessary-and-under-no-circumstances-to-be-done-without-with-casements—but the meat-salesmen at Smithfield were patriots. In their dire extremity the Germans have been trying to make them of cellulose.

Amongst the things both combatants most want is leather. One of the most impressive efforts we non-combatants have been watching, since August 1914, is an army growing, near us and next us, with apparently an unlimited supply of leather belts, leather trappings, leather saddlery—leather harness for man and beast. Yet they tell me that the price of leather since the War began has appreciated by 140 per cent. This may be so; but, as Joseph Finsbury remarked in ‘The Wrong Box,’ ‘there is nothing in the whole field of commerce more surprising than the fluctuations of the leather market. Its sensitiveness may be described as morbid.’ But Joseph was no business-man, and kept in the background of the office a capable Scot who was understood to have a certain talent for book-keeping. Readers of Stevenson will remember that nobody had ever made money out of Finsbury Brothers, Leather-merchants, except the capable Scot who retired (after his discharge) to the neighbourhood of Banff, and built a castle with his profits. There are still many capable Scots about, and this may, to some extent, account for the present price of Sam Browne belts.

There must have been well over 150,000 Sam Browne belts made since the War began. A widespread belief—at any rate, amongst the junior members of the Army—is that Sam Browne was an American; possibly some slight confusion existed in their dear young minds between the inventor of the belt and John Brown whose ‘body lies,’ &c. The inventor of this useful cincture was, however, Sir Samuel James Browne (1824-1901), G.C.B., K.C.S.I., the well-known Indian fighter, who lost an arm, and gained a V.C. by his gallantry during the Mutiny. He was for a time the military member of the Governor-General’s Council, and he commanded the first division of the Peshawar Field Force during the Afghan War of 1878-9. The 22nd Regiment in the Indian Army, a frontier force, is known as Sam Browne’s Cavalry.

The belt was first used unofficially, but it gradually found favour with the authorities, and it is mentioned officially in the regulations drawn up for the Straits Settlements in 1891, and for Egypt and West Africa in 1894. It was only on April 24, 1900, that the pattern was ‘sealed,’ and adopted as a general item of equipment for all officers on Active Service.

Anything that seriously destroys the continuity of the integument of our oxen, which interferes with the ‘wholeness’ of the hide which is the basis of leather, clearly affects—and affects detrimentally—an important munition of war. The bot- or warble-fly does this. But it does more: its attacks materially lessen the value of the beef which potentially lies beneath the hide, and thus in a double sense the warble-fly is the enemy of man whether he be soldier or sailor. Further, its attacks seriously lessen the milk-supply of the country.

Amongst the numerous families into which the true flies (Diptera) are divided, none are more harmful to human enterprise than that of the Oestridae, or bot-flies, inasmuch as every single species and every single member of this family passes its larval stage within the tissues of some vertebrate host, and frequently in those of domesticated cattle; sometimes even in man himself. One of the commonest genera of this family of flies is Hypoderma, which is represented in our islands, and in many other parts of the world where domesticated cattle are reared, by two species—H. bovis and H. lineatum, both commonly known as bot- or warble-flies.

The harm caused by these larvae, living as they do in the tissues of the body, beneath the skin, by piercing holes through the integument or skin, whereby they make their exit from the ‘warble’ or subcutaneous tumour in which they have passed their latest larval stage, is almost incalculable.

Miss Ormerod, who for so many years kept alight the lamp of economic entomology in England, published some statistics on this subject towards the end of the last century. In 1888, out of slightly over 100,000 hides dealt with in the Newcastle cattle and skin market, 60,000 were ‘warbled,’ and the loss to the trade amounted to £15,000. The same year at Nottingham 8500 out of 35,000 hides were largely spoiled; at Manchester 83,500 out of 250,000 suffered from the same cause: the losses in these towns being estimated for the year in question at about £2000 and £17,000 respectively. Taking the average from all sources in England, Miss Ormerod estimated the fall in value at from 5s. to 6s. on every warbled hide. The most riddled hides—that is, those with the most punctures—come to the sale-room during April and May, but the trouble extends from February to September.

There is also the loss caused by the warble to the butcher—and through the butcher to the Army Service Corps. The presence of the fly-larva, which is quite a large creature, induces chronic inflammation in the tissues, and a state of things known to the trade as ‘licked beef,’ and unless the meat-salesman cuts away the affected parts the meat is unsaleable in the market, or greatly depreciated in value. The average loss to the butcher on a warbled carcass is estimated at 6s. 8d.

Finally there is a loss to the stock-raiser and dairy farmer. We shall have occasion later to refer to the curious psychological effect the warble-fly has upon the cattle, causing them to ‘gad’ or stampede in wild gallops, which interferes with fattening, deteriorates the milk-supply, and is especially injurious to cows with calf. Mr. Imms, in his most useful summary of the warble-fly, tells us that the loss due to H. lineatum in America is calculated at 28 per cent. of their total value of all the cattle in the States. Some authorities place the total loss to the agricultural community in England at £2,000,000, others at £7,000,000, a year, whilst others estimate that the loss amounts to about £1 sterling on every head of horned cattle.

Curiously enough, the fly itself is rarely seen, and still more rarely taken. Mr. Imms records only two specimens of H. bovis in the collections of the British Museum, and but fifteen of H. lineatum. A similar scarcity of imagos in public collections obtains on the other side of the Atlantic, where for many years the last-named species was alone recognised. Two years ago, however, Dr. Hadwen, working in Canada, established the widespread existence of H. bovis in the Dominion; almost certainly it also occurs in the States; but Dr. Hadwen had to send to Dublin for specimens with which to confirm his find. None existed in the collections in Ottawa, and a ‘request for a specimen ... from the Bureau of Entomology at Washington, D.C., could not be granted owing to a scarcity of specimen’! These statements are interesting, since at present the tanneries of Canada are working night and day to help our shortage in leather at home.

H. bovis measures ⅝ in. in length, H. lineatum, somewhat less robust, ½ in.; the hairy covering of the last named is of a foxy red at the tail end, while that of H. bovis is yellow, both at the tail end and towards the front of the body. The flies are most abundant during July and August, though they are believed to occur throughout the summer. At Athenry (co. Galway) H. lineatum is common by the middle of May. They fly very rapidly, and are difficult to follow with the eye. They rejoice in warm, sunny weather, and remain in retirement during cold or cloudy days. Hadwen describes the egg-laying by the female ‘as a sort of frenzied process, the fly striking’ with its ovipositor twenty or thirty times rapidly, then leaving the animal for fifteen minutes or so, when the process was repeated. The eggs are attached one at a time to the hairs of the cattle and very close to the base of each hair, not near the tip, where the horse bot-fly deposits its ova. The eggs of H. bovis are scattered and isolated; those of H. lineatum are arranged in rows of some seven or more half-way up the hair and are contiguous. The favourite region for placing the eggs is on the hock and on the back of the knee, or on the thighs and flanks, and hence the American cowboys call the insect the ‘heel-fly.’ Undoubtedly by standing with their legs in water the herd is delivered from the pest—at any rate, for the time.

The eggs are large, 1·25 mm. in length, and enclosed in a whitish shell, which is prolonged behind into a brownish foot, and this foot, which exudes some sticky excretion, adheres to the ruminant’s hairs. The foot of the egg-shell, in fact, consists of two lobes or valves, which clasp the hair between their sticky inner surfaces.

Within the egg the youngest of the four larval stages is maturing. When hatched it is less than 1 mm. long, but it is ‘a terror for its size,’ being armed with a formidable spine and two hooks in the mouth, and with rows of strong spines on all the body-segments. Later, we find a second stage, very much smoother and less spiny than the first and this lies within the tissues of the host, embedded in its muscles and membranes, notably in the submucous coat of the gullet; and now the question confronts us, which once confronted George III apropos of the apple in the apple dumpling, ‘How the devil did it get in?’ There seems to be with Hypoderma but two possible modes of entrance into the body of its host—that is, domesticated cattle: (1) The eggs, or the newly hatched larvae, are licked up by the tongue, as are the eggs of the horse bot-fly—and this might be held to explain the not infrequent occurrence of the second larval stage in the walls of the oesophagus; or (2) the larvae bore their way directly through the skin. From experiments carried on for several years which show that cattle unable to lick themselves are not protected from warbles, Professor G. H. Carpenter of the Royal College of Science, Dublin, concluded that the larvae do not enter by the mouth. During the summer of 1914, he and his able assistant, the late Mr. T. R. Hewitt, definitely proved that ‘the newly hatched maggot does bore through the skin of cattle’; probably after an ecdysis they find their way to the submucous coat and muscles of the gullet, and here for a while they rest. I quote from the account of Carpenter and Hewitt some of their most crucial experiments carried out at the Athenry and Ballyhaise Stations of the Irish Department of Agriculture:—

Perhaps in the first stage they may be carried by the blood stream. They seem in their second larval stage to wander freely through the tissues, especially through the muscular tissues, of the body of their host—usually working upwards, and not infrequently reaching the neighbourhood of the vertebral column before taking up—still in the second larval stage—their final position, where their presence gives rise to the ‘warbles,’ or subcutaneous cysts or tumours, in which the third and fourth larval stages are passed.

It seems odd that an insect pest, which so seriously affects our supply of leather, of meat, and of milk, should have been studied for over a century and yet conceal its chief secret from man. But the problem is much more difficult than the layman thinks.

Whatever be the route the maggot travels through the body of the calf or cow, by the spring the fourth larval stage—when it is about an inch long, and perhaps half as much in breadth—is reached in the ‘warble’ or cyst, under the skin. Here, nourished by the products of the inflammation it sets up, and breathing by two spiracles at the hinder end of its body, which are directed to the opening of the ‘warble’ which it has pierced through the skin, the larva rests until one fine morning it pushes its way, aided by its stout bristles, through the opening and tumbles into the outer world.

Apparently it does not think much of its new surroundings, for it loses no time in hiding under some clod of earth or stone or crevice in the soil, and straightway turns into a dark brown pupa or chrysalis. This stage lasts three to four weeks, and then the perfect fly emerges, and will soon be ready to lay her eggs on some new victim.

As a rule it is the yearlings who suffer most, and then the two-year-olds; the older cattle being comparatively immune. The inexplicable terror which the warble-fly induces in its victims is testified to on all hands, but has never been adequately explained. Hypoderma does not bite, neither does it sting. Many other blood-sucking insects, whose puncture must involve some pain, are tolerated by cattle with a flick of the tail, or are frightened off by a gesture of the head; but the presence of the warble-fly induces a mysterious fear which rapidly spreads through a herd, and results in a general stampede—often referred to by cattle-breeders as the ‘gad.’ This terror communicates itself even to the ‘stalled ox,’ and cattle confined within cowsheds show symptoms of extraordinary unrest when the fly is abroad amongst their kin in the pastures. The resulting evils are, of course, far graver in the unlimited prairies of the West—the great cattle-breeding districts of the United States and Canada—than in our carefully hedged or fenced meadows. A great many ‘dips,’ ointments, and chemical solutions have been recommended for the prevention of the grubs in cattle, but none have proved entirely satisfactory. The tedious method of removing the grub from the tumour is the only safe one. This can be done by the mere pressure of the fingers when the grub is nearly mature and ready to leave its host, or by the use of small forceps should the grub be young and recalcitrant. Once removed the grub should be immediately destroyed, and some such antiseptic as coal-tar applied to the lips of the vacated tumour.