Change of Diet 



agricultural point of view. What is much 

 less familiar to us, because it touches us less 

 nearly, is the zoology of the insect, that is to 

 say, the selection which it makes, to feed 

 its larva, of this or that animal species, to 

 the exclusion of others. The subject is so 

 vast that a volume were not sufficient to ex- 

 haust it; besides, data are lacking in the vast 

 majority of cases. It is reserved for a still 

 very distant future to raise this point of 

 biology to the level already reached by the 

 question of vegetable diet. It will be enough 

 if I contribute a few observations scattered 

 through my writings or my notes. 



What does the Wasp addicted to a preda- 

 tory life eat, of course in the larval state? 

 Now, to begin with, we see natural sections 

 which adopt as their prey different species 

 of one and the same order, in one and the 

 same group. Thus the Ammophilae hunt 

 exclusively the larvae of the night-flying 

 Moths. This taste is shared by the Eu- 

 menes,^ a very different genus. The Spheges 

 and Tachytes are addicted to Orthoptera; 

 the Cerceres, apart from a few exceptions, 

 are faithful to the Weevil; both the Phi- 



1 Cf. The Mason-iuasps, by J. Henri Fabre, translated 

 by Alexander Teixeira de Mattos: chap. i. — Translator's 

 Note. 



169 



