THE BEMBICENE WASPS 23 



of these had completed their growth and were encased in 

 cells * * * but in every instance an immature larva in some 

 stage of development was also found in the burrow. In 

 no case, however, was more than one developing larva found 

 in any burrow. In one burrow with four branches three 

 contained matured and encased larvae ,and the fourth, 

 just newly constructed, contained two recently killed 

 house-flies, on one of which was found an unhatched egg. 

 From the data given above it would appear that the wasp 

 rears only one larva at a time." 



This interesting note recorded from Wilson, Kansas, 

 which differs so widely from our observations on the num- 

 ber of chambers to each burrow, shows that the wasps of 

 Dr. Parker's little colony of nubilipennis have acquired the 

 economical adaptation of using their burrows for more than 

 one chamber. It has been a matter of doubt whether Bem- 

 l>ix makes one burrow and carries that larva through its 

 infancy before beginning the next, or whether she keeps up 

 more than one domicile at a time. The Peckhams think, 

 from some experiments, that B. spinolae takes care of only 

 one nest at a time, and from our observations on the per- 

 manent closing of the nest early in the season with only a 

 single young one within, we think it probable that, in our 

 colony, the second burrow is constructed only after the first 

 has been completed. When we consider (as will appear 

 later) how poor the dissemination is in this species, we can 

 easily see how a digression of making three to five chambers 

 to a tunnel may easily become a habit and finally a family 

 characteristic and may become constant in the colony. Dr. 

 Parker states that these wasps had nested in this spot an- 

 nually for a number of years. 



Hence the establishment of a very pretty and economical 

 habit. At the same time one must recognize a new habit, 

 correlative of the multiplicity of cells, having arisen here, 



