32 WASP STUDIES AFIELD 



particular in sealing up that dead larva will always be a 

 mystery. Another mother spent equal pains in permanently 

 closing a burrow which later proved to be stark empty. In 

 yet another sealed burrow we found, besides the newly- 

 pupated larva, a spoonful or more of debris wings and 

 legs and besides this sixteen whole untouched flies, show- 

 ing how her solicitude had oversupplied the larva. The flies 

 were all dead; never in dealing with B. nubilipennis did we 

 find them alive or paralyzed, nor with the thorax crushed. 

 In this nest we found also a pair of wings of the bee-fly, 

 Spogostylum anale Say, which is parasitic on mud-wasps, 

 but here it had been brought in for food. 



The contents of the chambers and the occupancy of the 

 holes by the diggers are little understood; 4 as yet, the line 

 of difference between the normal and the abnormal use of 

 the burrows has not been drawn. 



Not a few holes have been followed to their end only to 

 find the nest all ready for occupancy and the mother wasp 

 calmly resting at the bottom. Under these circumstances, 

 the hole was usually closed, fairly firmly, from within. 

 Of course, it may be that we chanced to interrupt her 

 at a time when she had just completed her burrow, but 

 this condition occurred so frequently that such a chance 

 would have been highly improbable ; hence we suspect that 

 she uses her burrow not only for nidification but also, to 

 a considerable extent, as her own domicile. To be sure, 

 the gallery near the mouth of the burrow is always closed 

 by a mound of loose dirt when the wasp is digging the lower 

 part of the hole, but then the activity can be detected, at 

 short intervals, when the dirt moves or humps up from the 



4 On account of the frequent use of the field by the ball-players, 

 it was impossible to keep in connection with one mother or her one 

 nest long enough to get a connected story. Every effort was made to 

 revisit marked nests, but in every case the boys with the spiked shoes 

 obliterated them. 



