INDIRECT INJUKIES CAUSED BY INSECTS. 



127 



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 do- 

 mestic ; and the rein-deer is quite as much so to the Lap- 

 lander 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 gadfly ^ : 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 larvae 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. — The QEstri 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 manoeuvre is unnecessary, since 



1 Mr. Curtis {Brit. Ent. t. 106.) under the name of (Estrus pictus has figured 

 a tine 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. 



- Reaum. v. 69. Dictionnaire de Trevoux, article Cerf. 



