22 WASP STUDIES AFIELD 



forms, we have never found more than one chamber at the 

 bottom of the tunnel and one immature wasp therein. The 

 only nest having more than one organism was one which 

 contained a medium-sized larva feeding on flies and a much 

 smaller second one in the same and only chamber. The 

 slight resemblance of the two larvae caused us to doubt 

 whether they were of the same species, although the addi- 

 tional one was a Hymenopterous larva. On another oc- 

 casion, in digging up a burrow we found a second one in 

 the earth close beside the chamber that contained a large 

 larva ready to spin, but this probably did not belong to the 

 same nest. The wasps in their semi-gregariousness often 

 build their burrows in close juxtaposition, so the cells of 

 different nests seem to have only a thin partition of earth 

 between them. 



Parker, 3 however, finds that his B. nubilipennis has habits 

 similar to Philanthus, for he says : "The burrows * * * enter 

 the ground at an angle of 45. At a distance of from eight 

 to twelve inches from the entrance lateral branches are given 

 off, which serve as brood chambers for the larvae. At the 

 time of my observation no burrow was found with more 

 than five of these chambers; most had four and a few had 

 only three. In the chambers more than one larva may be 

 reared, in which case the first is placed at the extreme end 

 of the chamber and when full grown and encased a wall 

 is placed across the chamber and another larva reared be- 

 tween this and the main part of the burrow. * * * These 

 observations were made on August 18 and 19, and although 

 many burrows were opened only larvae were found. Many 



3 Ohio Nat. 10 : 163-165. Despite the fact that Cresson described the 

 species in 1872, this is the only paper that we can find which has bio- 

 logical data on this species, excepting Robertson, Trans. Acad. Sci. 

 St. Louis 6: 458, 1894, who found the adults feeding on the flowers 

 of four species of plants. 



