LETTER V.

_INJURIES CAUSED BY INSECTS._

INDIRECT INJURIES.

Having detailed to you the _direct_ injuries which we suffer from insects, I am now to call your attention to their _indirect_ attacks upon us, or the injury which they do our property; and under this view also you will own, with the fullest conviction, that they are not beings that can with prudence or safety be disregarded or despised. Our property, at least that part exposed to the annoyance of these creatures, may be regarded as consisting of animal and vegetable productions, and that in two states; when they are living, namely, and after they are dead. I shall therefore endeavour to give you a sketch of the mischief which they occasion, first to our _living animal_ property, then to our _living vegetable_ property; and lastly to our _dead stock_, whether animal or vegetable.

Next to our own persons, the _animals_ which we employ in our business or pleasures, or fatten for food, individually considered, are the most valuable part of our possessions--and at certain seasons, hosts of insects of various kinds are incessant in their assaults upon most of them.--To begin with that noble animal the _horse_.--See him, when turned out to his pasture, unable to touch a morsel of the food he has earned by his labours. He flies to the shade, evidently in great uneasiness, where he stands continually stamping from the pain produced by the insertion of the weapons sheathed in the proboscis of a little fly (_Stomoxys calcitrans_) before noticed as attacking ourselves[231]. This alights upon him sometimes in one place and sometimes in another, and never lets him rest while the day lasts.--See him again when in harness and travelling. He is bathed in blood flowing from innumerable wounds made by the knives and lancets of various horse-flies (_Tabanus_, L.), which assail him as he goes, and allow him no respite[232]; and consider that even this is nothing to what he suffers in other climates from the same pest. In North America, vast clouds of different species--so abundant as to obscure every distant object, and so severe in their bite as to merit the appellation of burning flies--cover and torment the horses to such a degree as to excite compassion even in the hearts of the pack-horsemen. Some of them are nearly as big as humble-bees; and, when they pierce the skin and veins of the unhappy beast, make so large an orifice that, besides what they suck, the blood flows down its neck, sides, and shoulders in large drops like tears, till, to use Bartram's expression, "they are all in a gore of blood." Both the dog-tick and the American tick before mentioned, especially the latter, also infest the horse. Kalm affirms, that he has seen the under parts of the belly, and other places of the body, so covered by them, that he could not introduce the point of a knife between them. They were deeply buried in the flesh; and in one instance that he witnessed, the miserable creature was so exhausted by continual suction, that it fell, and afterwards died in great agonies[233].

No quadruped is more infested by the gad-fly, sometimes also improperly called the breese[234], than the horse. In this country no fewer than three species attack it. The most common sort, known by the name of the horse-bee (_Gasterophilus Equi_), deposits its eggs (which being covered with a slimy substance adhere to the hairs) on such parts of the body as the animal can reach with its tongue; and thus, unconscious of what it is doing, it unwarily introduces into its own citadel the troops of its enemy.--Another species (_G. hæmorrhoidalis_) is still more troublesome to it, ovipositing upon the lips; and in its endeavours to effect this, from the excessive titillation it occasions, giving the poor beast the most distressing uneasiness. At the sight of this fly horses are always much agitated, tossing their heads about in the air to drive it away; and, if this does not answer, galloping off to a distant part of their pasture, and, as their last resource, taking refuge in the water, where the gad-flies never follow them. We learn from Reaumur, that in France the grooms, when they observe any bots (which is the vulgar name for the larvæ and pupæ of these flies) about the anus of a horse or in its dung, thrust their hand into the passage to search for more; but this seems a useless precaution, which must occasion the animal great pain to answer no good end: for when the bots are passing through the body, having ceased feeding, they can do no further injury. In Sweden, as De Geer informs us, they act much more sensibly: those that have the care of horses are accustomed to clean their mouths and throats with a particular kind of brush, by which method they free them from these disagreeable inmates before they have got into the stomach, or can be at all prejudicial to them[235].

Providence has doubtless created these animals to answer some beneficial purpose; and Mr. Clark's judicious conjectures are an index which points to the very kind of good our cattle may derive from them, as acting the part of perpetual stimuli or blisters: yet when they exceed certain limits, as is often the case with similar animals employed for purposes equally beneficial, they become certainly the causes of disease, and sometimes of death.

How troublesome and teasing is that cloud of flies (_Anthomyia meteorica_) which you must often have noticed in your summer rides, hovering round the head and neck of your horse, accompanying him as he goes, and causing a perpetual tossing of the former[236]!--And still more annoying in Lapland, as we learn from Linné[237], is the furious assault of the minute horse-gnat, (_Culex equinus_, L.) which infests these beasts in infinite numbers, running under the mane and amongst the hair, and piercing the skin to suck their blood.--An insect of the same genus is related to attack them in a particular district in India in so tremendous a manner as to cause incurable cancers, which finally destroy them[238].--But of all the insect tormentors of these useful creatures, there is none more trying to them than the forest-fly (_Hippobosca equina_). Attaching themselves to the parts least covered with hair, particularly under the belly between the hind legs, they irritate the quietest horse, and make him kick so as often to hazard the safety of his rider or driver. This singular animal runs sideways or backwards like a crab; and, being furnished with an unusual number of claws, it adheres so firmly that it is not easy to take it off; and even if you succeed in this, its substance is so hard, that by the utmost pressure of your finger and thumb it is difficult to kill it; and if you let it go with life, it will immediately return to the charge.--Amongst the insect plagues of horses, I should also have enumerated the larva of _Lixus paraplecticus_, which Linné considers as the cause of the equine disease, called in Sweden, after the _Phellandrium aquaticum_, "_Stâkra_," had not the observations of the accurate De Geer rendered it doubtful whether the insect be at all connected with this malady[239].

Another quadruped contributing greatly to our domestic comfort, from which we derive a considerable portion of our animal food, and which, on account of its patient and laborious character when employed in agriculture, is an excellent substitute for the horse, (you will directly perceive I am speaking of the _ox_, whether male or female,) is also not exempt from insect domination. At certain seasons the whole terrified herd, with their tails in the air, or turned upon their backs, or stiffly stretched out in the direction of the spine, gallop about their pastures, making the country re-echo with their lowings, and finding no rest till they get into the water. Their appearance and motions are at this time so grotesque, clumsy, and seemingly unnatural, that we are tempted rather to laugh at the poor beasts than to pity them, though evidently in a situation of great terror and distress. The cause of all this agitation and restlessness is a small gad-fly (_Œ. Bovis_), less than the horse-bee, the object of which, though it be not to bite them, but merely to oviposit in their hides, is not put into execution without giving them considerable pain.

When oxen are employed in agriculture, the attack of this fly is often attended with great danger, since they then become perfectly unmanageable; and, whether in harness or yoked to the plough, will run directly forward. At the season when the Œstrus infests them, close attention should be paid, and their harness so constructed that they may easily be let loose.

Reaumur has minutely described the ovipositor, or singular organ by which these insects are enabled to bore a round hole in the skin of the animal and deposit their eggs in the wound. The anus of the female is furnished with a tube of a corneous substance, consisting of four pieces, which, like the pieces of a telescope, are retractile within each other. The last of these terminates in five points, three of which are longer than the others, and hooked: when united together they form an instrument very much like an auger or gimlet; only, having these points, it can bite with more effect[240]. He thinks the infliction of the wound is not attended by much pain, except where very sensible nerves are injured, when the animal, appearing to be seized with a kind of phrensy, begins to gambol, and run with such swiftness that nothing can stop it. From this semblance of temporary madness in oxen when pursued and bored by the Œstrus, the Greeks applied the term to any sudden fit of fury or violent impulse in the human species, calling such ebullitions an _Œstrus_. The female fly is observed to be very expeditious in oviposition, not more than a few seconds; and while she is performing the operation, the animal attempts to lash her off, as it does other flies, with its tail. The circular hole, made by the auger just described, always continues open, and increases in diameter as the larva increases in size; thus enabling it to receive a sufficient supply of air by means of its anal respiratory plates, which are usually near the orifice.--But though these insects thus torment and terrify our cattle, they do them no material injury. Indeed they occasion considerable tumours under the skin, where the bots reside, varying in number from three or four to thirty or forty; but these seem unattended by any pain, and are so far from being injurious, that they are rather regarded as proofs of the goodness of the animal, since these flies only attack young and healthy subjects. The tanners also prefer those hides that have the greatest number of bot-holes in them, which are always the best and strongest[241].

The Stomoxys, and several of the other flies before enumerated, as well as the dog and American ticks, are as prejudicial to the ox as to the horse. One species of Hippobosca I have reason to believe is appropriated to them; yet, since a single specimen only has hitherto been taken[242], little can be said with respect to it.--A worse pest than any hitherto enumerated, is a minute fly, concerning the genus of which there is some doubt, Fabricius considering it as a Rhagio, (_R. columbaschensis_,) and Latreille as a Simulium[243]; but to whatever genus it may belong, it is certainly a most destructive little creature. In Servia and the Bannat it attacks the cattle in infinite numbers, penetrates, according to Fabricius, their generative organs, but according to other accounts their nose and ears, and by its poisonous bite destroys them in the short space of four or five hours. Much injury was sustained in 1813 from this insect in the palatinate of Arad in Hungary and in the Bannat; in Banlack not fewer than two hundred horned cattle perishing from its attacks, and in Versetz, five hundred. It appears towards the latter end of April or beginning of May in such indescribable swarms as to resemble clouds, proceeding as some think from the region of Mehadia, but according to others from Turkey. Its approach is the signal for universal alarm. The cattle fly from their pastures; and the herdsman hastens to shut up his cows in the house, or, when at a distance from home, to kindle fires, the smoke of which is found to drive off this terrible assailant. Of this the cattle are sensible, and as soon as attacked run towards the smoke, and are generally preserved by it[244].

Tabani in this country do not seem to annoy our oxen so much as they do our horses: perhaps for this immunity they may be indebted to the thickness of their hides; but Virgil's beautiful description of the annoyance that the Grecian Œstrus, called by the Romans Asilus, belongs evidently to one of the _Tabanidæ_. As the passage has not been very correctly translated, I shall turn poet on the occasion, and attempt to give it you in a new dress.

Through waving groves where Selo's torrent flows, And where, Alborno, thy green Ilex grows, Myriads of insects flutter in the gloom, (Œstrus in Greece, Asilus named at Rome,) Fierce and of cruel hum. By the dire sound Driven from the woods and shady glens around The universal herds in terror fly; Their lowings shake the woods and shake the sky, And Negro's arid shore----

In some parts of Africa also insects of this tribe do incredible mischief. What would you think, should you be told that one species of fly drives both inhabitants and their cattle from a whole district? Yet the terrible _Tsaltsalya_ or _Zimb_ of Bruce (and the world seems now disposed to give more credit to the accounts of that traveller) has power to produce such an effect. This fly, which is a native of Abyssinia, both from its habits and the figure, appears to belong to the _Tabanidæ_, and perhaps is congenerous with the _Œstrus_ of the Greeks[245].

Small as this insect is, we must acknowledge the elephant, rhinoceros, lion and tiger vastly his inferior. The appearance, nay the very sound of it occasions more trepidation, movements and disorder both in the human and brute creation, than whole herds of the most ferocious wild beasts in tenfold greater numbers than they ever are would produce. As soon as this plague appears, and their buzzing is heard, all the cattle forsake their food, and run wildly about the plain till they die worn out with fatigue, fright, and hunger. No remedy remains for the residents on such spots but to leave the black earth and hasten down to the sands of Atbara, and there they remain while the rains last. Camels, and even elephants and rhinoceroses, though the two last coat themselves with an armour of mud, are attacked by this winged assassin and afflicted with numerous tumours. All the inhabitants of the sea-coast of Melinda down to Cape Gardefui, to Saba and the south of the Red Sea, are obliged in the beginning of the rainy season to remove to the next sand to prevent all their stock of cattle from being destroyed. This is no partial emigration--the inhabitants of all the countries from the mountains of Abyssinia northward, to the confluence of the Nile and Astaboras, are once a year obliged to change their abode and seek protection in the sands of Beja; nor is there any alternative or means of avoiding this, though a hostile band were in the way capable of spoiling them of half their substance[246]. This fly is truly a Beelzebub[247]: and perhaps it was this, or some species related to it, that was the prototype of the Philistine idol worshiped under that name and in the form of a fly.

I must not conclude this subject of insects hurtful to our cattle, without noticing a beetle much talked of by the ancients for its mischievous properties in this respect. You will soon and rightly conjecture that I am speaking of the Buprestis[248], so called from the injury which it has been supposed to occasion to oxen or kine.

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.

Amongst our most valuable domestic animals I shall be very unjust and ungrateful, if I do not enumerate those industrious little creatures the _bees_, from whose incessant labours and heaven-taught art we derive the two precious productions of honey and wax. They also are infested by numerous insect-enemies, some of which attack the bees themselves, while others despoil them of their treasures.--They have parasites of a peculiar genus, although at present regarded as belonging to Pediculus[262], and mites (_Gamasus gymnopterorum_) are frequently injurious to them. That universal plunderer the wasp, and his formidable congener the hornet, often seize and devour them, sometimes ripping open their body to come at the honey, and at others carrying off that part in which it is situated. The former frequently takes possession of a hive, having either destroyed or driven away its inhabitants, and consumes all the honey it contains. Nay there are certain idlers of their own species, called by apiarists corsair-bees, which plunder the hives of the industrious.--From the curious account which Latreille has given us of _Philanthus apivorus_, a wasp-like insect, it appears that great havoc is made by it of the unsuspecting workers, which it seizes while intent upon their daily labours, and carries off to feed its young[263]. Another insect, which one would not have suspected of marauding propensities, must here be introduced. Kuhn informs us, that long ago (in 1799) some monks who kept bees, observing that they made an unusual noise, lifted up the hive, when an animal flew out, which to their great surprise no doubt, for they at first took it for a bat, proved to be the death's-head hawk-moth (_Acherontia Atropos_), already celebrated as the innocent cause of alarm[264]; and he remembers that several, some years before, had been found dead in the bee-houses[265]. M. Huber, also, in 1804 discovered that it had made its way into his hives and those of his vicinity, and had robbed them of their honey. In Africa we are told it has the same propensity; which the Hottentots observing, in order to monopolize the honey of the wild bees, have persuaded the colonists that it inflicts a mortal wound[266]. This moth has the faculty of emitting a remarkable sound, which he supposes may produce an effect upon the bees of a hive somewhat similar to that caused by the voice of their queen, which as soon as uttered strikes them motionless, and thus it may be enabled to commit with impunity such devastation in the midst of myriads of armed bands[267]. The larvæ of two species of moth (_Galleria Cereana_, and _Mellonella_) exhibit equal hardihood with equal impunity. They indeed pass the whole of their initiatory state in the midst of the combs. Yet in spite of the stings of the bees of a whole republic, they continue their depredations unmolested, sheltering themselves in tubes made of grains of wax, and lined with silken tapestry, spun and wove by themselves, which the bees (however disposed they may be to revenge the mischief which they do them, by devouring, what to all other animals would be indigestible, their wax,) are unable to penetrate. These larvæ are sometimes so numerous in a hive, and commit such extensive ravages, as to force the poor bees to desert it and seek another habitation.

I shall not delay you longer upon this subject by detailing what _wild animals_ suffer from insects, further than by observing that the two creatures of this description in which we are rather interested, the _hare_ and the _rabbit_, do not escape their attack. The hare in Lapland is more tormented by the gnats than any other quadruped. To avoid this pest it is obliged to leave the cover of the woods in full day, and seek the plains: hence the hunters say, that of three litters which a hare produces in a year, the first dies by the cold, the second by gnats, and only the third escapes and comes to maturity[268].--We learn from the ingenious Mr. Clark, that the American rabbit and hare are infested by the largest species of Œstrus[269] yet discovered; and our domestic rabbits sometimes swarm with the bed-bug. This was the case with some kept by two young gentlemen at my house last summer to such a degree, that I found it necessary to have them killed.

Nor are the _inhabitants of the waters_ sheltered by their peculiar element from these universal assailants. The larvæ of Dytisci fixing themselves by their suctorious mandibles to the body of _fish_, doubtless destroy an infinite number of the young fry of our ponds. Some species of salmon (_Salmo Fario_, L.) are the food of an animal which Linné has arranged under Pediculus; and probably many others of the finny tribes may, like the birds, have their peculiar parasites. Even _shell-fish_ do not escape, for the _Nymphon grossipes_ enters the shell of the muscle and devours its inhabitant.

I am, &c.

FOOTNOTES:

[231] See above, p. 110.

[232] Once travelling through Cambridgeshire with a brother entomologist in a gig, our horse was in the condition here described, from the attack of _Tabanus rusticus_.

[233] De Geer, vii. 158.

[234] See Mr. W. S. MacLeay in _Linn. Trans._ xiv. 355--.

[235] De Geer, vi. 295.

[236] _Amœn. Acad._ iii. 358.

[237] Linn. _Flor. Lapp._ 376. _Lach. Lapp._ i. 233, 234. This insect from Linné's description is probably no _Culex_, but perhaps a _Simulium_, Latr. (_Simulia_, Meig.).

[238] _Life of General Thomas_, 186.

[239] Linn. _It. Scand._ 182. De Geer, v. 227-30.

[240] PLATE XVI. FIG. 3. Mr. Clark, however, is of opinion that the Œstrus does not pierce the skin of the animal, but only glues its eggs to it. _Essay on the Bots of Horses and other Animals_, p. 47.

[241] Much of the information here collected is taken from Reaum. iv. _Mem._ 12; and Clark in _Linn. Trans._ iii. 289.

[242] The writer of the present letter is possessor of this specimen, which he took on himself in a field where oxen were feeding. PLATE V. FIG. 1.

[243] In the _Systema Antliatorum_ (p. 56) Fabricius most strangely considers this insect as synonymous with _Culex reptans_, L. calling it _Scatopse reptans_, and dropping his former reference to Pallas, and account of its injurious properties. Meigen (_Dipt._ i. 294) makes this insect a _Simulia_ under the name of _S. maculata_.

[244] Fabr. _Ent. Syst. Em._ iv. 276. 22. Latr. _Hist. Nat._ &c. xiv. 283. _Leipz. Zeit._ Jul. 5, 1813, quoted in Germar's _Mag. der Ent._ ii. 185.

[245] It is by no means clear that the _Œstrus_ of modern entomologists is synonymous with the insects which the Greeks distinguish by that name. Aristotle not only describes these as _blood-suckers_ (_Hist. Animal._ l. viii. c. 11.) but also as furnished with a _strong proboscis_ (l. iv. c. 7.). He observes likewise that they are produced from an animal inhabiting the _waters_, in the vicinity of which they most abound (l. viii. c. 7.). And Ælian (_Hist._ l. vi. c. 38.) gives nearly the same account. Comparing the Œstrus with the Myops (synonymous perhaps with _Tabanus_, Latr., except that Aristotle affirms that its larvæ live in wood, l. v. c. 19,) he says, the Œstrus for a fly is one of the largest; it has a stiff and large sting, (meaning a proboscis,) and emits a certain humming and harsh sound--but the Myops is like the Cynomyia--it hums more loudly than the Œstrus, though it has a smaller sting.

These characters and circumstances do not at all agree with the modern Œstrus, which, so far from being a blood-sucker furnished with a strong proboscis, has scarcely any mouth. It shuns also the vicinity of water, to which our cattle generally fly as a refuge from it. It seems more probable that the Œstrus of Greece was related to Bruce's _Zimb_, represented in his figure with a long proboscis, which makes its appearance in the neighbourhood of rivers, and belongs to the _Tabanidæ_. For further information the reader should consult Mr. W. S. MacLeay's learned paper on the insect called _Oistros_ and _Asilus_ by the ancients. _Linn. Trans._ xiv. 353--.

[246] Bruce's _Travels_, 8vo. ii. 315.

[247] Heb. זבוב בעל literally "Lord-Fly." See 2 Kings, i. 2; and Bochart. _Hierozoic._ ps. ii. l. 4. c. 9. p. 490.

[248] _Burn-Cow_ or _Ox_, from βους bos, and πρηθω inflammo. M. Latreille translates it _Crève-bœuf_, but improperly.

[249] _Annales du Muséum_.--X^e Ann. N^o xi. p. 129.

[250] _Observations de plusieurs Singularités, &c._ l. i. c. 45. p. 73 of the Edition in Sir Joseph Banks's Library.

[251] _Hist. Nat._ l. xxix. c. 4.

[252] See Curtis, _Brit. Ent._ t. 142.

[253] Mr. Curtis (_Brit. Ent._ t. 106) under the name of _Œstrus pictus_ has figured a fine species of Gad-fly taken in the New Forest, which he conjectures may be bred from the Deer. It may probably be one of the species here alluded to.

[254] Reaum. v. 69. _Dictionnaire de Trevoux_, article _Cerf_.

[255] For the account of the Œstrus, of the deer, see Reaum. v. 67-77.

[256] Linn. _Lach. Lapp._ ii. 45. In the passage here referred to, Linné speaks of two species of Œstrus, though the mode of expression indicates that he considered them as the same. One was _Œ. nasalis_ from which they freed themselves by snorting, &c., the other _Œ. Tarandi_ which formed the pustules in their backs. In _Syst. Nat._ 969. 3. he strangely observes under the former species, "_Habitat in equorum_ fauce, per nares intrans!" confounding probably _Œ. veterinus_ of Mr. Clark with the true _Œ. nasalis_.

[257] _Lach. Lapp._ i. 280.

[258] _Flor. Lapp._ 79.

[259] Linn. _Flor. Lapp._ 379.

[260] Mr. Kittoe.

[261] PLATE V. FIG. 3.

[262] _Melittophagus_, Mus. Kirby. See _Mon. Ap. Angl._ ii. 168. I copy the following memorandum respecting _M. Melittæ_ from my common-place-book, May 7, 1812. On the flowers of Ficaria, Taraxacum and Bellis, I found a great number of this insect, which seemed extremely restless, running here and there over the flowers, and over each other, with great swiftness mounting the anthers, and sometimes lifting themselves up above them, as if looking for something. One or two of them leaped upon my hand. Near one of these flowers I found a small _Andrena_ or _Halictus_, upon which some of these creatures were busy sucking the poor animal, so that it seemed unable to fly away. When disclosed from the egg, I imagine they get on the top of these flowers to attach themselves to any of the _Andrenidæ_ that may alight on them, or come sufficiently near for them to leap on it.--K.

[263] Latreille, _Hist. des Fourmis_, 307-20.

[264] See above, p. 34.

[265] _Naturforscher_ Stk. xvi. 74.

[266] Quoted from Campbell's _Travels in South Africa_, in the _Quarterly Review for July_ 1815. 315.

[267] Huber. _Pref._ xi-xiii.

[268] De Geer, ii. 83.

[269] Considered by Mr. Clark as a new genus, which he has named _Cuterebra_, and of which he has described three species. _Essay on the Bots of Horses, &c._ _p._ 63. _t._ 2. _f._ 24-29.