22 
when they are come to maturity. In the tree nest 
a somewhat different arrangement is adopted. In- 
stead of round pillar-like braces, thin slips of the 
paper of which the whole nest is composed, but 
made stiffer for this purpose, are continued along 
the edges of a number of cells, so as not to interfere 
with the inmates, and are finally fixed to the layer 
below. The number of these fastenings varies in 
every layer. 
In examining the cells of some of the nests, a diffi- 
culty occurs of which I can offer no very satisfactory 
explanation. The cells of the uppermost layers are 
in some instances gnawed away, so as to be much too 
shallow for the reception of a grub. They all bear 
the marks of the teeth of the wasps, and are not 
eaten down with much regularity. The nests in 
which this peculiarity occurred, were taken about 
the middle of August, and I can only account for 
this appearance by supposing that at that time of 
year no more neuters were necessary for carrying on 
the works of the nest; and as any eggs deposited 
then, could not be matured before the middle of 
September, the cells were no longer wanted, and 
were gnawed away to give more room to the in- 
mates. The female cells, being still occupied by the 
young in their various stages, were left entire. The 
larve that remain in the nest when the cold weather 
sets in, are always destroyed by the survivors, who 
find themselves unable any longer to procure food 
for them. The males are chiefly employed in this 
work, and may sometimes be seen dragging the 
grubs to the outside of the nest, where they are left 
to perish. 
The females leave the nest in October, and seek 
