1928] The Nesting Habits of the Pulp-Making Bee 107 
the plug was inserted it was sufficiently thick to make room for 
a passageway. No. 4 was also dead, in the same place where she 
was that morning. Whether exhaustion, delay or weakness 
caused her death I do not know. 
One wonders if we may not have a case of the transitional 
or developmental state of a habit. Most bees in nests having 
real partitions, attack and perforate the partition itself; Prosoyis 
modestus, we find escapes by cutting a new channel through the 
pith around the hard partition. The habit of this species of 
Alcidamea seems to be a reversion to a former habit, i. e., an 
attack upon the plug, modified by a new trick of removing bits 
of pith adjacent to the plug in order to loosen it, and this side 
cutting varying in amount from the removal of a few bits to the 
tearing out of enough of the pith in one place before the plug is 
dislodged to permit the passage of the insect’s body, and in some 
cases the biting out of the pith at the sides without any evidence 
of attack upon the plug itself. One wonders whether Prosoyis 
went through these stages of the arduous struggle with the hard 
discs before eventually adopting the easier method of detouring 
through the soft pith, and, if so, how long the species continued 
its struggle and suffering before is learned its lesson well. 
Either the difficulty of the exit or the change of method or 
some such factor was costing the species a heavy toll of lives at 
emerging time. More than half of those I watched died before 
escaping from their secure imprisonment, or died of exhaustion 
immediately after gaining their liberty. Is this because of the 
difficulty of their situation, or must hardship or death always be 
the price of change? 
Among the parasites which were found infesting the nests 
of these bees were Stelis lateralis Cress., [J. C. Crawford], Eyis- 
tenia osmice [S. A. Rohwer] and Stelis sexmaculata Ash., [J. C. 
Crawford]. My twigs were gathered too late in the season to 
study the relation between parasites and host. A very important 
paper has been written by Dr. S. Graenicher 3 who was fortunate 
in finding nests with both parasite and host larvae in the cells. 
sBull. Wise. Nat. Hist. Soc. 3; 153-167, 1905. 
