58 College of Forestry 
and where their egg-galleries arise from an egg-gallery of a 
larger form (Fig. 11), the brood burrows constructed are . 
likely to be relatively short. The reason for this is believed 
to be that these small beetles tend to live socially in a com- 
mon ‘“ assembly chamber ” and where this is of adequate size 
for the members occupying it, the burrowers do not extend 
their mines to any great distance from the general meeting 
place: 7. e., each female may construct several short galleries. 
On the other hand, when the numbers are greater and the 
central assembly chamber inadequate to accommodate all 
members of the colony at once, the females are likely to 
construct their egg-galleries longer and to lay all of their eggs 
in one gallery. Indeed, in some cases, the gallery as finally 
made may represent the joint work of several females. This 
very likely is the case in the branched galleries which are 
by no means uncommon in the larger engravings having 
numerous egg-galleries, several of which may be seen in 
Figs. 12 and 13. 
In the material at hand, the length of the egg-galleries 
varies from less than half an inch to two and three-fourths 
inches. No satisfactory counts of the number of larvae to 
a gallery could be made because the numerous larvae had 
destroyed most of the egg niches with their winding larval 
mines. These larval burrows are not on the surface of the 
sapwood but in the middle region of the inner bark. 
Our observation seem to indicate that this insect spends 
the winter usually in the beetle stage, as adults begin to 
appear under the bark during the late summer, and these 
emerge the following spring. In the region of Cranberry 
Lake, the senior author has taken a number of colonies of 
these just after they had invaded the abandoned or still 
occupied burrows of other insects. In one case (June 9, 
1915) a group of about twenty individuals were observed in 
the burrow of a larva of Monohammus scutellatus. Only a 
few of these had started egg-galleries, the remainder being 
grouped together in a little recess in the side of the burrow 
of the roundheaded borer near the ventilation opening. 
