WASPS, SOCIAL AND SOLITARY 



Bembex, like Philanthus, and some species of Sphex, 

 lives in a sort of semi-social state, a number of individ- 

 uals occupying the same space of ground, although each 

 one has its separate nest. Bembex, however, differs 

 from these genera and from almost all of the solitary 

 wasps in her habit of feeding her young from day to day, 

 or rather from hour to hour, as long as it remains in the 

 larval state. This difference in her maternal cares as 

 compared with those of other species results in a less 

 numerous progeny. The larva, for a period of two weeks, 

 demands constant attention from the mother, so that a 

 second egg cannot be laid until the first-born has gone 

 into its cocoon, unless, indeed, she feeds two larvae at 

 once, which does not seem probable. The season of 

 work is ten or twelve weeks, so that Wesenberg is prob- 

 ably correct in allowing only five or six young ones to 

 each mother for the summer. 



In watching our wasps we found that the new nests 

 were usually made in the outskirts of the colony, which 

 was thus continually extending its limits. Like many 

 other species, Bembex has great difficulty in deciding 

 just where to dig. Our Sphex made three beginnings 

 before finally settling down. The only Ammophila that 

 we watched from the beginning changed her place after 

 working for ten minutes. P. quinquenotatus often tried 



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