Modern writers have been much divided in their opinion to what genus this celebrated insect belongs. All indeed have regarded it as of the Coleoptera order; but here their agreement ceases. Linné should seem to have looked upon it as a species of the genus to which he has given its name; but these, being timber insects, are not very likely to be swallowed by cattle with their food. Geoffroy thinks it to be a Carabus or Cicindela, but with as little reason, since the species of these genera do not feed amongst the herbage; and though they are sometimes found running there, yet their motions are so rapid, that it is not very likely that cattle would often swallow them while feeding.
M. Latreille, in an ingenious essay on this insect[249], suspects it to belong to the genus Melöe, and as this feeds upon herbs, (M. Proscarabæus and M. violaceus, upon the Ranunculi, so widely disseminated in our pastures,) his opinion seems to rest upon more solid grounds than that of his predecessors; but yet I think the insect in question rather belongs to Mylabris, and for the following reason.
In order rightly to ascertain what insect this really was, we must endeavour to trace it in the country in which it received its name and character. This country was certainly Greece; and there such an animal, retaining nearly its old name, and accused of being the cause of the same injury to cattle, still exists. For Belon informs us that on Mount Athos there is found a winged insect like the blister-beetle, but yellow, larger, and of a very offensive smell, which feeds upon various plants, and is called Voupristi by the Caloyers or Monks, who assert that when horses or other cattle even feed upon the herbs which the animals have touched, they die from inflammation, and that it is an immediate poison to oxen[250]. This therefore most probably was the Buprestis of the Greek writers; and as Pliny usually compiled from them, it may be regarded as his also, which he tells us was a caustic insect and prepared in the same manner as the blister-beetle[251]. He further observes that it was scarce in Italy. The Greek insect of Mount Athos M. Latreille supposes to be a Mylabris, and in this I agree with him; and therefore this is the proper genus to which the original Greek Buprestis, the true type of the insect in question, ought to be referred, and not Melöe.
Whether this animal be really guilty to the extent of which it is accused, admits of considerable doubt; but as I have not the means of ascertaining this, I shall leave the question for others who are better informed to decide.
But, of all our cattle none are more valuable and important to us than our flocks; to them we look not only for a principal part of our food, but also for clothing and even light. Thick as is their coat of wool, it does not shield them from the attack of all-subduing insects: on the contrary it affords a comfortable shelter to one of their enemies of this class, regarded by Linné as a species of Hippobosca, but properly separated from that genus by Latreille under the name of Melophagus[252]. This is commonly called the sheep-louse, and is so tenacious of life, that we are told by Ray it will exist in a fleece twelve months after it is shorn, and its excrements are said to give a green tinge to the wool very difficult to be discharged.—You have doubtless often observed in the heat of the day the sheep shaking their heads and striking the ground violently with their fore feet; or running away and getting into ruts, dry dusty spots or gravel pits, where crowding together they hold their noses close to the ground. The object of all these actions and movements is to keep the gad-fly appropriated to them (Œ. Ovis) from getting at their nostrils, on the inner margin of which they lay their eggs, from whence the maggots make their way into the head, feeding in the maxillary and frontal sinuses on the mucilage there produced. When full-grown, they fall through the nostrils to the ground and assume the pupa. Whether the animal suffers much pain from these troublesome assailants is not ascertained. Sometimes the maggots make their way even into the brain. I have been informed by a very accurate and intelligent friend, that, on opening the head of one of his sheep which died in consequence of a vertigo, three maggots were found in it in a line just above the eyes, and that behind them there was a bladder of water.—Perhaps you are not aware that the bots we are speaking of, or rather those in the head of goats, have been prescribed as a remedy for the epilepsy, and that from the tripod of Delphos. Yet so we are told on the authority of Alexander Trallien. Whether Democrates, who consulted the oracle, was cured by this remedy does not appear; the story shows however that the ancients were aware of the station of these larvæ.—The common saying that a whimsical person is maggoty, or has got maggots in his head, perhaps arose from the freaks the sheep have been observed to exhibit when infested by their bots.—The flesh-fly is also a great annoyance to the fleecy tribe, especially in fenny countries; and if constant attention be not paid them, they are soon devoured by its insatiable larvæ. In Lincolnshire, the principal profit of the druggists is derived from the sale of a mercurial ointment used to destroy them.—In tropical countries the sheep frequently suffer from the ants. Bosman relates that when in Guinea, if one of his was attacked by them in the night, which often happened, it was invariably destroyed, and was so expeditiously devoured that in the morning only the skeleton would be left.
Of our domestic animals the least infested by insects, I mean as to the number of species that attack it, is the swine. With the exception of its louse, which seems to annoy it principally by exciting a violent itching, it is exposed to scarcely any other plague of this class, unless we may suppose that it is the biting of flies, which in hot weather drives it to "its wallowing in the mire."
Under this head we may include the deer tribe, for, though often wild, those kept in parks may strictly be deemed domestic; and the rein-deer is quite as much so to the Laplander, as our oxen and kine are to us. We learn from Reaumur that the fallow-deer is subject to the attack of two species of gad-fly[253]: one, which, like that of the ox, deposits its eggs in an orifice it makes in the skin of the animal, and so produces tumours; and another in imitation of that of the sheep, ovipositing in such a manner that its larvæ when hatched can make their way into the head, where they take their station in a cavity near the pharynx. He relates a curious notion of the hunters with respect to these two species. Conceiving them both to be the same, they imagine that they mine for themselves a painful path under the skin to the root of the horns; which is their common rendezvous from all parts of the body; where, by uniting their labours and gnawing indefatigably, they occasion the annual casting of these ornamental as well as powerful arms. This fable, improbable and ridiculous as it is, has had the sanction of grave authorities[254].—The Œstri last mentioned inhabit, in considerable numbers, two fleshy bags as big as a hen's egg, and of a similar shape, near the root of the tongue. Reaumur took between sixty and seventy bots from one of them, and even then some had escaped. What other purpose these two remarkable purses are intended to answer, it is not easy to conjecture. He supposes that the parent fly must enter the nostrils of the deer, and pass down the air passages to oviposit in them: but probably such a manœuvre is unnecessary, since there seems no reason, supposing the eggs to be laid in the nostrils, why the larva when hatched cannot itself make its way down to the above station, as easily as that of the sheep into the maxillary sinuses. Or, which perhaps is more likely, when the animal draws in the air, the eggs or larvae may be carried down with it, in both cases, to the place assigned to them by Providence[255].
No animal, however, is so cruelly tormented by Œstri as the rein-deer; for besides one synonymous apparently with this of the deer (Œ. nasalis) from which they endeavour to relieve themselves by snorting and blowing[256], they have a second which produces bots under their skin; not improbably the same species that in a similar way attacks the latter, as I have stated above. We have heard that the vaccine disease is derived from the cow and the horse, and the small-pox is said to have originated in the heels of the camel: but neither the ingenious Dr. Jenner nor any other writer on this subject has informed us that the rein-deer is subject to the distemper last named; yet Linné quotes the learned work of a Swedish physician on Syphilis, who gravely gives this as a fact[257]!! The inoculator, in truth, is the gad-fly, the tumours it causes are the pustules, and its larvæ are the pus.—It is astonishing how dreadfully these poor animals in hot weather are terrified and injured by them: ten of these flies will put a herd of five hundred into the greatest agitation. They cannot stand still a minute, no not a moment, without changing their posture, puffing and blowing, sneezing and snorting, stamping and tossing continually; every individual trembling and pushing its neighbour about. The ovipositor of this fly is similar to that of the ox-breese, consisting of several tubular joints which slip into each other; and therefore Linné was probably mistaken in supposing that it lays its eggs upon the skin of the animal, and that the bot, when it appears, eats its way through it[258]: there can be little doubt (or else what is the use of such an apparatus) that it bores a hole in the skin and there deposits the eggs. About the beginning of July the rein-deer sheds its hair, which then stands erect—at this time the fly is always fluttering about it, and takes its opportunity to oviposit. The bots remain under the skin through the whole winter, and grow to the size of an acorn. Six or eight of these are often to be found in a single rein-deer that has only seen one winter; and these so emaciate them, that frequently one third of their number perish in consequence. Even those that are full grown suffer greatly from this insect. The fly follows the animals over precipices, valleys, the snow-covered mountains, and even the highest alps; to which in order to avoid it they often fly with great swiftness in a direction contrary to the wind. By this constant agitation and endeavour to escape from the attack of their enemy they are kept from eating during the day, standing always upon the watch, with erect ears and attentive eyes, that they may observe whether it comes near them[259]. The rein-deer are teased also by a peculiar species of Tabanus (T. tarandinus) which, by a singular instinct, instead of their skin, makes its incision in their horns when tender.
Our dogs, the faithful guardians of our other domestic animals and possessions, the attached companions of our walks, and instruments of many of our pleasures and amusements, cannot defend themselves from insect annoyance. They have their peculiar louse, and the flea sucks their blood in common with that of their master: you must also often have noticed how much they suffer from the dog-tick, which, when once it has fixed itself in their flesh, will in a short time, from the size of a pin's head, so swell itself out by gorging their blood, that it will equal in dimensions what is called the tick-bean. In the West Indies these ticks, or one like them, get into the ears and head of the dogs, and so annoy them and wear them out that they either die or are obliged to be killed[260].
Some of the most esteemed dainties of our tables are supplied from such of the winged part of the creation as we have domesticated. These also have a louse (Nirmus) appropriated to them, and the gorgeous peacock is infested by one of extraordinary dimensions and singular form[261]. Pigeons, in addition, often swarm with the bed-bug, which makes it advisable never to have their lockers fixed to a dwelling-house. In their young, if your curiosity urges you to examine them, you may find the larva of the flea, which in its perfect state often swarms in poultry.