V. 



Further Notes upon Habits of Insects. 



IN a former review contributed to Natural Science (vol. iii., p. 267), 

 I referred to Herr Verhoeff's researches into the habits of the 

 social and solitary wasps and bees. This interesting subject has 

 lately received further attention from a French observer, M. Paul 

 Marchal, who (i, 2) gives details of the habits of two genera of the 

 digging or fossorial wasps — Bemhex and Crabro. He observed Bembex 

 rostrata on coast sand-hills, and watched the operations of digging the 

 nest and catching the prey to serve as food for the grubs. The prey 

 of Bembex consists of species of Eristalis — large two-winged hovering- 

 flies. M. Marchal collected a stock of these insects and, having 

 attached the end of a silk thread to a leg of each, conveyed them to 

 the haunts of the Bembex, where he let one fly, retaining the other 

 end of the thread. The Bembex seized the Eristalis with great rapidity, 

 held the fly back downwards beneath her body and pierced it with 

 her sting. On releasing the fly from its captor, it was found to be 

 quite motionless, except for feeble movements of the jaws and 

 abdominal viscera, and in a few days it was dead and began to dry 

 up. Fabre established the fact that Bembex brings a fresh fly each 

 day to her progeny ; hence there is no necessity that the life of the 

 victim should be prolonged, as in the case of the prey of many sand- 

 wasps. 



On some occasions M. Marchal was surprised to find the Bembices 

 engaged in furious and apparently aimless digging, giving the observer 

 " I'impression d'etre de veritables maniaques." His captive flies were 

 neglected, or one put directly in front of the Bembex only caused the 

 wasp to move away a few inches and recommence her strange 

 pastime. This is clearly an aberration of the instinct of nest-making, 

 and M. Marchal suggests that it may overcome the insect when, by 

 reason of a high wind or otherwise, she is prevented from hunting. 



Crabro cephalotes was observed to make her nest in an old felled 

 walnut tree, by forming a tunnel curved like an irregular 3, from 

 which proceeded branches, some of them forked: at the end of these 

 were the cells where the eggs were laid and the grubs hatched. Each 

 cell was sealed with a plug of sawdust filhng up its branch of the 

 tunnel, after the wasp had placed in it from six to ten paralysed flies 

 — mostly Syrphi. In carrying these into the nest, she was observed 



