XVI THE BEMBEX 231 



tuously treated. I subtract then from the sum 

 obtained, and reduce it to sixty pieces of medium 

 size, between that of the house-fly and Eristalis tenax. 

 This would be about the number of Diptera given by 

 the mother to the larva when the prey is middle- 

 sized, as is the case with all the Bembecids of my 

 district except B. rostrata and B. bidentata, which 

 especially favour the gadfly. For these the number 

 of slain would be from one to two dozen, according 

 to the size of the Dipteron, which varies greatly in 

 the gadfly species. 



In order not to return to the kind of provisions, I 

 give a list of the Diptera observed in the burrows of 

 the six kinds of Bembex, which are the subject of 

 this essay. 



(i) B. olivacea, Rossi. Once only have I seen 

 this species, at Cavaillon, preying on Lucilia Caesar. 

 The five next are common round Avignon. 



(2) B. oculata, Jur The Dipteron upon which 

 the egg is laid is generally a Sphaerophoria, especially 

 S. scripta ; sometimes it is a Geron gibbosus. Further 

 provender consisted in Stomoxys calcitrans, Pollenia 

 ruficollis, P. rudis, Pipiza nigripes, Syrphus corollae, 

 Onesia viarum, Calliphora vomitoria, Echinomyia 

 intermedia, Sarcophaga agricola, Musca domestica. 

 The usual food was Stomoxys calcitrans, of which I 

 have found fifty or sixty in a single burrow. 



(3) Bembex tarsata, Lat. It, too, lays its egg on 

 Sphaerophoria scripta ; but it also hunts Anthrax 

 flava, Bombylius nitidulus, Eristalis aeneus, E. sepul- 

 chralis, Merodon spinipes, Syrphus corollae, Helophilus 

 trivittatus, Zodion notatum. Its favourite prey con- 

 sists in Bombylius and Anthrax. 



