150 INDIRECT INJURIES CAUSED BY INSECTS. 



Reaumur has minutely described the ovipositor, or sin- 

 gular 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 a . He thinks the in- 

 fliction of the wound is not attended by much pain, ex- 

 cept 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 no- 

 thing can stop it. From this semblance of temporary 

 madness in oxen when pursued and bored by the CEstrus, 

 the Greeks applied the term to any sudden fit of fury or 

 violent impulse in the human species, calling such ebulli- 

 tions an CEstrus. 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 suf- 

 ficient 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 



1 Plate XVI. Fig. 3. Mr. Clark, however, is of opinion that the 

 CEstrus does not pierce the skin of the animal, but only glues its e"gs 

 to it. Essay on the Bols of Homes and other Animals, p. 4/. 



