ys ay aie bea * . ~ Fi 
Sic Van ai ! Neh ; Hl 
INSECTS INJURIOUS TO THE PINE. . Lis 
tion, he writes us that it isa species of Pityophthorus, not described. Dr, 
Leconte adds: ‘‘ Blanchard writes that Hypophleus tenuis depredates on 
this species.” (Leconte afterwards identifies it as probably P. puberulus.) 
36. NXyleborus impressus Eichhoft. 
Leconte states that this species occurs in Georgia under pine bark. 
37. PINE TIMBER-BEETLE. 
Pityophthorus materiarius Fitch. 
Order COLEOPTERA; family SCOLYTID®. 
In the interior of the sap wood, mining slender straight cylindrical burrows in a 
transverse direction, parallel with the outer surface, from which very short straight — 
lateral galleries branch off at right angles above and below; a rather slender cylin- 
drical black shining bark-beetle, 0.15 long, with pale dull yellow legs and antenne, 
the fore part of its thorax and of its wing-covers tinged with reddish yellow; the 
thorax equaling two-thirds the length of the wing-covers with .a small elevated 
tubercle in the middle, forward of which it is rough from minute elevated points; the 
wing-covers with rows of minute punctures, their tips rounded, 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 immediately 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 females are much the most numer- 
ous, 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 sur- 
face and at right angles with the fibers 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 my 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 representation of this bur- 
*Not reproduced. 
\ 
