340 AFFECTION OF INSECTS FOR THEIR YOUNG. 



young, she ever carefully drops her eggs. The larva? 

 of the gad-fly (CEstrus Equi), whose history has been be- 

 fore described to you % are destined to live in the sto- 

 mach of the horse. How shall the parent, a two-winged 

 fly, convey them thither? By a mode truly extraor- 

 dinary. 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 slight- 

 est 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 occurs 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 dilem- 

 ma ; and I will then ask you if she does not discover 

 a provident forethought, a depth of instinct, which al- 

 most 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 con- 

 fines them almost 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 b ? 



Not less admirable is the parental instinct of that vast 

 * P. 14(5, &c. «« Clark in Linn. Trans, iii. 304. 



