406 INSECT' ARCHITECTURE. 



An insect pest (named (Estrut by the Greeks, 

 By us Asilus) : fierce with jarring 1mm 

 It darts towards the herd, driving them terrified 

 From glade to glade, while the far sky resounds. 

 And woods and rivers' banks echo their lowings. 



Had we not other instances to adduce, of similar 

 terror caused among sheep, deer, and horses, hy in- 

 sects of the same genus, which are ascertained not 

 to penetrate the skin, we should not have hesitated to 

 conclude that Vallisnieri and Reaumur are right, and 

 Mr. Bracey Clark wrong. In the strictly similar in- 

 stance of reindeer fly (CEstrus tarandi, Linn.), we 

 have the high authority of Linnseus for the fact, that 

 it lays its eggs upon the skin. 



" I remarked," he says, " with astonishment, how 

 greatly the reindeer are incommoded in hot weather, 

 insomuch that they cannot stand still a minute, no 

 not a moment, without changing their posture, start- 

 ing, puffing and blowing continually, and all on 

 account of a little fly. Even though amongst a herd 

 of perhaps five hundred reindeer there were not 

 above ten of those flies, every one of the herd trem- 

 bled and kept pushing its neighbour about. The 

 fly, meanwhile, was trying every means to get at 

 them ; but it no sooner touched any part of their 

 bodies, than they made an immediate effort to shake 

 it off. I caught one of these insects as it was flying 

 along with its tail protruded, which had at its extremity 

 a small linear orifice perfectly white. The tail itself 

 consisted of four or five tubular joints, slipping into 

 each other like a pocket spying-glass, which this fly, 

 like others, has a power of contracting at pleasure."* 



In another work, he is still more explicit. " This 

 well-known fly," he says, " hovers the whole day 

 over the back of the reindeer, with its tail protruded 



* Linnseus; Lachesis Lapponica, July 19th. 



