30 College of Forestry. 
ing position, his elytral declivity will be parallel with the 
surface of the bark (Fig. 13). As soon as the entrance bur- 
row reaches such a depth that the declivity is even with the 
bark, it is continued at a sharp angle to its original course 
(Fig. 10) so that it nearly im smediately becomes parallel with 
the surface of the bark. Lf the burrow under construction 
be one intended for breeding purposes, as most of those enter- 
ing through the surface of the bark are, the male construct- 
ing it soon begins widening it out to form a nuptial chamber. 
The length of the entrance burrows varies in different brood 
burrows. In some it is little more than the length of the indi- 
vidual building it, i. e. the nuptial chamber is excavated as 
soon as a position parallel with the surface is reached, while 
in other cases the entrance gallery may be carried hor izontally 
for a distance of several millimeters before it is widened 
out to form the nuptial chamber (Fig. 15). 
The nuptial chamber is a cavity of irregular shape and 
variable size (Fig. 23, a, b, c,d). Itisa flat chamber just 
high enough to accommodate the body of P. hopkinsi. It 
may be coreenucied upon the surface of the sapwood, may 
even grove the sapwood, or may be entirely in the bark. The 
depth at which it occurs does not depend upon the thickness 
of the bark but is determined by the length of the specimen 
constructing it. The size varies greatly and does not depend 
on the length of time the burrow has been occupied, but ap- 
parently depends upon the length of the period in which the 
male constructing it remains a bachelor. It is found on 
opening burrows started at the same time that the nuptial 
chamber in those occupied only by the male constructing it 
are larger than those containing from one to five females 
with radiating ege galleries. The reason for this is clear. 
As long as the male does not succeed in attracting one or 
more females, he continues working at his burrow and con- 
tinues feeding upon the frass he excavates. As soon as the 
females share the burrows with him, his activities are changed 
and he now spends most of his time guarding the entrance 
and removing the frass excavated by the females from their 
ege galleries. He doubtless feeds upon this latter and there- 
5 5° 
