60 College of Forestry. 
Both the entrance gallery and the nuptial chamber of 
the brood-burrow is constructed entirely by the male, this 
work requiring from two to six days. 
The burrow is always started at some roughened or in- 
jured place in the bark, this being necessary in order that 
the worker may have suitable foothold. As soon as the 
gallery is deep enough, the beetle burrows by bracing the 
dorsum of his prothorax against one side of the burrow 
while the mandibles are brought to bear upon the other side. 
The rugosities upon the prothorax, which are in the form of 
flat spines pointing backward, anchor the body when they 
are pressed against the sides of the burrow and prevent it 
from slipping backward but readily allow the body to slip 
forward farther into the burrow. 
The entrance burrow is carried into the bark at such an 
angle that, when it has been excavated far enough that the 
entire body of the insect is covered, the elytral declivity of 
the burrower lies parallel to the bark and completely closes 
the entrance. | 
As soon as the entire body of the beetle is below the 
surface of the bark, the direction of the entrance burrow is 
changed so it extends parallel with the surface. It is 
usually continued for about two millimeters — the length of 
the insect — and then is widened out to form a flat irregular 
chamber — the nuptial chamber. 
The nuptial chamber may lie upon the surface of the 
sapwood, may groove the sapwood, or may lie entirely in the 
bark, dependent upon the thickness of the latter. 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 of the nuptial chamber does not 
depend upon the length of time it has been occupied, but 
upon the period that the male constructing it remains with- 
out a mate, as he continues burrowing until the advent of 
one or more females. ! 
After the burrow has been carried below the surface of 
the bark it is impossible to dislodge the male by any ordi- 
nary means. He will respond to either intense light or to 
