1927J 
Nesting Habits of a Solitary Bee 
201 
resulting from this gave off three or four short galleries each of 
which ended at a cell. Hence there were approximately six 
cells to each nest. If it is to be assumed that each female is 
capable of laying fifteen eggs, then more than one nest must 
have been provisioned by each bee. She probably finished one 
nest and then constructed another. Surely a female was not 
taking care of two nests simultaneously as has been observed in 
the case of Dianthidium sayi Ckll. The reason for the latter 
assumption lies in the fact that in one colony of Spinoliella, 
consisting of about forty nests, I collected thirty-seven females. 
Then, when it was visited a few days later, there were just four 
nests being provisioned by as many bees. This is conclusive 
evidence that there was but one bee to a nest and visa versa. 
As in the case of Perdita opuntioe Ckll . 3 the pollen is con- 
structed into a sphere and one end of the egg is inserted into 
this . 4 Furthermore, the cells for the larvae have their walls 
similarly smoothed as though the insect had lapped them with 
its tongue. And, finally, it is interesting to note that the larvae 
of these two bees are almost identical. Each has the typical 
double row of spines down its back. Some of the larvae of S. 
australior are just as white as are those of Perdita opuntice; others 
however, which have probably consumed an over-abundance of 
pollen, are somewhat yellow. 
In the key by T. D. A. Cockerell and W. W. Robbins (TO) 
the bees of these two genera differ principally from one another 
in the length of the marginal cell. In Perdita it is short and 
broadly truncate; in Spinoliella it is narrow and long. 
It is hoped that further comparative work can be done on 
the nesting habits of Perdita and Spinoliella which resemble one 
another in so many respects. 
3 See Custer (’28). _ 
4 Malyshev (’25), in Russia, states that the larvae of Systropha planides 
so start eating the pollen ball that it lies on their ventral surface, on top of 
them, thus preventing it from drying out from coming in contact with the 
cell wall. In the nest shown in Fig. 1 above, I found a larva in a similar 
position. This larva is pictured directly beneath the entrance. 
