44 PHIL RAU AND NELLIE RAU 



one barn near a stream, and care was taken to select only those 

 which apparently contained pupae. The good nests may be 

 distinguished from the old nests by the openings of egress which 

 the latter contain. This point of distinction may not always 

 be relied upon since occasionally these holes have been replastered 

 with mud or wax by tenants of the old nests, such as Osmia 

 bees or small Trypoxylon or even Eumenid wasps. 



Unfortunately for the variation studies, the most of the cells 

 were either parasitized by Melittobia or they had been elimi- 

 nated in the larval stages by various agencies, so that only a 

 meagre handful of normal adults came from all this collection. 

 Variation studies were defeated, but there arose at the same 

 time the equally important and inviting problem of the rate 

 and causes of this appalling elimination. 



So with this large number of nests on hand I took up the 

 task of opening each cell and tabulating its contents. Since 

 the resulting tables are too unwieldy to be practical for publi- 

 cation, it seems best to give the total results of each class of 

 contents of the nests, adding thereto the details of some of the 

 most interesting mother-wasp behavior as revealed by a study 

 of the contents of her cells. 



The 643 nests which constituted this lot had a total of 4,397 

 cells. The number of cells in each nest varied from 1 to 36, 

 as presented in the table below. 



The Peckhams 19 found, before the season was over, the number 



of cells to a nest to be 5 or 6 and the most they ever found was 2 1 . 



Out of 4,397 cells I obtained only 172 good adults in June. 



10 



Loc. cit., p. 178. 



