56 INSECT LIFE iv 



expect from what L6on Dufour has told us of the 

 habits of the Cerceris bupresticida, I could not 

 repress my astonishment at the sight of the singular 

 collection which I had made. His Cerceris, though 

 it limits itself to one genus, yet takes any species 

 within that limit, but the more exclusive C. tuber- 

 culata preys exclusively on Cleonus ophthalmicus. 

 On looking through my booty I met with but one 

 single exception, and that belonged to a closely 

 allied species, C. alternans — one which I never met 

 with again in my frequent visits to the Cerceris. 

 Later researches furnished me with a second ex- 

 ception, Bothynoderes albidus, and these are all. 

 Can a specially succulent and savoury prey explain 

 this predilection for a single species ? Do the larvae 

 find in this unvaried diet juices which suit them 

 peculiarly, and which they would not find elsewhere? 

 I do not think so, and if L^on Dufour's Cerceris 

 hunted all the kinds of Buprestids, no doubt it was 

 because they all have the same nutritive properties. 

 But this must generally be the case with all the 

 Curculionidae ; their alimentary properties must be 

 identical, and in that case this amazing choice can 

 only be one of size, and therefore of economy of 

 labour and time. Our Cerceris, the giant of its 

 race, chooses C. ophthalmicus as the largest in our 

 district, and perhaps the commonest. But if this 

 favourite prey fail, it must fall back upon other 

 species, even if smaller, as is proved by the two 

 exceptions above mentioned. 



Moreover, it is by no means the only one to 

 hunt the long-nosed class of weevils. Many other 

 Cerceris, according to their size, strength, and the 



