46 College of Forestry 
It is perhaps worthy of remark that in engravings of P. 
rufipenms in spruce observed both in the Adirondacks and 
Catskills there is a greater preponderance of females than 
in the larch material from Crittenden. The exact signifi- 
cance of this can only be guessed at, but to one who has for 
a number of years spent several weeks in each of these 
regions at the season of the year when the greater number 
of these insects are establishing themselves in their new 
breeding quarters, an explanation which has occurred to the 
senior author may appeal with some force. The young adults 
are leaving their old hosts and entering new ones during the 
early and middle parts of June when violent rains are a 
nearly daily occurrence. It is the male which first leaves 
the old host and which makes the entrance burrow and 
prepares the nuptial chamber in the new host, while the 
female does not emerge from the old host until several days 
later. During the early construction of the new burrow the 
males are exposed to various dangers, and to one who knows 
in general the habits of bark beetles it is very apparent that 
in a rainy season, many lose their lives by the very frequent 
and violent rain storms. On the other hand the females, 
leaving the protection of the old host later, are not subject 
to so many dangers as a large percentage of them find nup- 
tial chambers alr eady prepared for their reception. 
Thus if the sexes occur in about equal proportions im the 
old host as has been shown to be the case in Pityogenes hop- 
kinsi, Swaine (Blackman, 1915), the preponderance of 
females over males in the new brood chambers would vary 
with the occurrence of storms at the time of transferring 
from old to new host. It is believed that the more equable 
climate in Erie county, N. Y., from which region the 
infested larch was obtained had allowed a larger number of 
males to establish their new breeding quarters than is usually 
possible in the Adirondacks and Catskills where violent 
storms are of nearly daily occurrence. 
Hopkins (1899, p. 248) has said that: “ Probably two 
or three broods may occur in one season — but my observa- 
tions lead me to believe that . . . there is generally but 
