Ecological and Behavior Notes 29 



it when she had her prey. I had known that they often 

 climb trees with their prey in order to be able better to 

 launch on wing with their heavy burden, but I had not 

 suspected that they first select a burrow, or that they 

 may use burrows made by others. She did not reappear, 

 and an attempt to dig up the rodent's burrow proved un- 

 successful. 



Microhembix monodonta Say. [S. A. Rohwer]. On a 

 large, bald area of white sand on a hilltop at Silica, many 

 of these little wasps were active. They were neither 

 digging nor dancing ; but they flew aimlessly about, drop- 

 ped to the ground and rested, whereupon a second would 

 often bump against the first. Although I watched for 

 about two hours, I could see no actual mating or nest 

 digging; hence I suspected that these were probably the 

 males just emerging. They flew near to the ground, and 

 it was with difficulty that the net could be manipulated to 

 effect their capture. This was on July 2, 1920. 



Bemhix spinolae. While on September 1 B. nubili- 

 pennis had entirely disappeared, we saw a female of B. 

 spinolae on September 16 just commencing her burrow. 

 In consideration of the fact that it would take her several 

 weeks to feed her young to maturity, this seemed sur- 

 prisingly poor physical economy. The site was a small 

 sandy area on a vacant city lot. On this spot the wasp 

 scratched some sand out at about eight different places 

 before she found one satisfactorj\ She scratched and 

 kicked the sand under her in much the same manner as 

 B. nubilipennis. She would go down and push the loose 

 soil up from below until the channel was full, then push 

 her way out through it, turn about with her head just 

 inside the channel and rapidly kick out the sand as she 

 retreated, (Plate VI fig. 8) repeat this several times, and 

 then go in again and work up more soil from the bottom. 



Bemhix nubilipennis. From June 15 we watched daily 

 for the 1919 population of this species, but they did not 

 come out until June 29; on the 30, they were there in 



