86 INDIRECT INJURIES CAUSED BY INSECTS. 



as it is, has had the sanction of grave authorities. 1 The (Estri last men- 

 tioned 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 in- 

 tended 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 pas- 

 sages to oviposit in them ; but probably such a manoeuvre 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 larva? may be carried down with it, in both cases, to the place assigned 

 to them by Providence. 2 



No animal, however, is so cruelly tormented by CEstri as the rein-deer; 

 for besides one synonymous apparently with this of the deer (CE. nasalis), 

 from which they endeavour to relieve themselves by snorting and blow- 

 ing 3 , they have a second which produces bots under their skin; not im- 

 probably 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 Linne quotes the learned work of a 

 Swedish physician on Syphilis, who gravely gives this as a fact ! ! 4 The 

 inoculator, in truth, is the gad-fly, the tumours it causes are the pustules, 

 and its larvae 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 can- 

 not stand still a minute, no not a moment, without changing their posture, 

 puffing and blowing, sneezing and snorting, stamping and tossing continu- 

 ally ; 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 Linne was 

 probably mistaken in supposing that it lays its eggs upon the skin of the 

 animal, and that the hot, when it appears, eats its way through it 5 : 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 



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



2 For the account of the CEstrus of the deer, see Reaum. v. 67 77. 



5 Linn. Lack. Lapp. ii. 45. In the passage here referred to, Linne speaks of two 

 species of (Estrns, though the mode of expression indicates that he considered them 

 as the same. One was CE. nasalis, from which they freed themselves by snorting, 

 &c., the other CE. 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 CE.veterinus of Mr. Clark with the 

 true CE. nasalis. 



* Loch. Lapp. L 280. 5 Flor. Lapp. 79. 



