AFFECTION OF INSECTS FOR THEIR YOUNG. 287 



offspring, however dissimilar to her own ; or at least in- 

 variably places her eggs, often defended from external injury 

 by a variety of admirable contrivances, in the exact spot 

 where, when hatched, the larvas can have access to it. — The 

 dragon fly is an inhabitant of the air, and could not exist in 

 water : yet in this last element, which is alone adapted for 

 her young, she ever carefully drops her eggs. The larva3 of 

 the gad-fly ((Estrus Equi), w^hose history has been before 

 described to you, are destined to live in the stomach of the 

 horse. How shall the parent, 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 hun- 

 dred 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 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 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 

 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 ? ^ 



Not less admirable is the parental instinct of that vast tribe 

 of insects already introduced to you by the name of Ichneu- 

 mons, 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, which in its larva state is not ex- 



1 Clark in Linn. Trans, iii. 304. 



