WASPS, SOCIAL AND SOLITARY 



that they go in to lay their eggs. According to Fabre, it 

 is the habit of the flies that are parasitic upon the half- 

 dozen species of Bembex that he has studied to seize the 

 moment at which the fly projects from under the abdo- 

 men of the wasp as she enters the nest ; and he has even 

 known them to lay two or three eggs on one fly in the 

 instant of time that its body was exposed. 



Fabre took a partly grown Bembex larva from the 

 nest, where it was surrounded by the remains of twenty 

 flies. He fed it generously, and it ate sixty-two more, 

 making a total of eighty-two in the eight days that 

 passed before the spinning of the cocoon. Our experi- 

 ments in this line gave similar results. We took charge 

 of a partly grown larva on the afternoon of August tenth, 

 and between that date and August fifteenth, when it 

 spun its cocoon, it ate forty-two house flies besides a big 

 Tabanus. 



Fabre thinks that under natural conditions the mother 

 does not give the larva all it can eat at one time, but pro- 

 vides it with what she considers a reasonable amount of 

 food, and keeps anything that she catches beyond this 

 out of its reach. He draws his conclusion from the fact 

 that he has found several flies in the tunnel leading to the 

 nest, while the larva had as many more close to it. It 

 would certainly" be convenient for Bembex to have a 



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