STATE AGRICULTURAL SOCIETY. 
727 
PINE. TRUNK. 
ed, the upper part of the declivity with a shallow longitudinal 
depression or groove along the suture, forming a slight notch. 
The insects belonging to the genus Tomicus and kindred genera 
of the same family by their habits divide themselves into two 
distinct groups. The larger portion of them reside in or imme¬ 
diately beneath the bark of different trees and are currently 
termed bark-beetles. But this designation is inappropriate for 
another portion of them which dwell in the interior of the wood, 
and there excavate their galleries. The name timber-beetles 
appears to be the most appropriate for these. Another point 
in which, from the observations of M. Perris, these two groups 
appear to differ in a remarkable manner, is the relative numbers 
of the two sexes. With the bark-beetles there are commonly 
several males in company with but one female, and the former 
appear to perform the chief part of the labor in the excavation 
of their galleries. With the timber-beetles, on the other hand, 
the femalos are much the most numerous, and probably mine 
their galleries without any assistance from the other sex. M. 
Perris states of one of the species, that upwards of fifty females 
were met with in the burrows they had excavated, without a 
single male being found there. 
It is the habit of these timber-beetles to penetrate the tree in 
a straight line, passing inwards through the bark and into the 
sap wood to a depth of from half an inch to two inches, and 
then abruptly turning they extend their burrow in another 
straight line parallel with the outer surface and at right angles 
with the fibres of the wood, for a length of two to six inches. 
The only instance in which the burrow of the species now under 
consideration has come under ray notice, was recently, in a billet 
of stove wood, which unfortunately did not contain the extreme 
end of the gallery. The annexed cut is an exact representa¬ 
tion of this burrow, in which a 
live and a dead beetle were 
found, both of them females, 
and the only specimens of this ^ - 1 n r== 
species which have come under Ul 
my observation. The transverse burrow was excavated in the 
sap wood at the depth of half an inch from its outer surface. 
