AFFECTIOX OF INSECTS FOR THEIR YOUNG. 341 



rent, a two-winged fly, convey them thither ? By a 

 mode truly extraordinary. Flying round the animal, 

 she curiously poises her body for an instant while she 

 glues a single egg to one of the hairs of his skin, and 

 repeats this process until she has fixed in a similar 

 way many hundred eggs. These, after a few days, on 

 the application of the slightest moisture attended by 

 warmth, hatch into little grubs. Whenever, therefore, 

 the horse chances to lick any part of his body to which 

 they are attached, the moisture of the tongue discloses 

 one or more grubs, which adhering to it by means of 

 the saliva are conveyed into the mouth, and thence find 

 their way into the stomach. But here a question oc- 

 curs to you. It is but a small portion of the horse's 

 body which he can reach with his tongue : what, you 

 ask, becomes of the eggs deposited on other parts ? I 

 will tell you how the gad-fly avoids this dilemma; and 

 I will then ask you if she does not discover a provident 

 forethought, a depth of instinct, which almost casts into 

 shade the boasted reason of man ? She places her eggs 

 only on those parts of the skin which the horse is able 

 to reach with his tongue; nay, she confines them al- 

 most exclusively to the knee or the shoulder, which he 

 is sure to lick. What could the most refined reason, the 

 most precise adaptation of means to an end, do more''? 

 Not less admirable is the parental instinct of that vast 

 tribe of insects already introduced to you by the name of 

 Ichneumons, whose young are destined to feed upon the 

 living bodies of other insects. These, as you know, are so 

 numerous, that scarcely an insect exists, but is in its larva 

 state exposed to the attacks of one or other of them ; and 



^ Clark in Linn, Trans, iii. 304. 



