THE PINE TIMBER-BEETLE. 719 
" 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 2 inches, and 
then abruptly turning they extend their burrow 
in another straight line parallel with the outer 
surface and at right angles with the fibers of the 
wood, for a length of 2 to 6 inches. The only in- 
stance in which the burrow of the species now 
under consideration has come under my notice 
was recently in a billet of stove wood, which un- 
fortunately did not contain the extreme end of 
the gallery. The annexed cut* is an exact repre- 
sentation of this burrow, in which a live and a 
dead beetle were found, both of them females, and 
the only specimens of this species which have 
J ^ l Fig. 249. — Gnathotrichus 
come under my observation. The transverse bur- materarius. Marx^. 
row was excavated in the sap-wood at the depth 
of half an inch from its outer surface. Near its middle it was crossed 
by another perforation extending from the outside directly towards 
the heart of the tree, which is indicated by a black dot in the figure ; 
and at this point the burrow curved slightly outwards towards the 
exterior surface, as represented in the section above the principal 
figure in the cut; and at its end on the left, where it passed out of the 
billet of wood, it commenced curving inwards towards the heart of the 
tree, Twelve lateral burrows of the same diameter as the transverse 
one extended upwards and two downwards, as shown in the figure, all 
of the same length, each one having been excavated probably by a 
single larva. The gallery of our insect thus differs widely from that of 
the European species (T. eurygaster Erichson) which mines in {he inte- 
rior of the pine, which has no lateral burrows branching off from it. 
"The presence of these timber-beetles in the wood can be distinguished 
from those which mine under the bark by the little piles of sawdust 
which they throw out at the mouth of their burrows, this dust being so 
much more white and clean, and not composed in part of the brown or 
rust colored particles of gnawed bark which are intermixed with the 
dust produced by the bark-beetles. (Fitch.) 
The beetle. — In addition to the short description of this beetle which is given above, 
it may be observed that the head is finely punctured, the punctures on the face giving 
out small pale yellowish hairs, while those on the vertex or crown are destitute of 
hairs, and there is a slight transverse elevation of the surface between the face and 
the vertex, from which an elevated smooth line extends backwards along the middle 
of the vertex. Thorax, when viewed from above, with its base transverse and rec- 
tilinear, its basal angles rectangular, its opposite sides parallel for a distance equal- 
ing the length of the base, and from thence rounded in a semicircle at its anterior, 
end ; its surface anteriorly with minute asperities, which, viewed vertically, appear 
like fine transverse wriukles; its basal half with very minute punctures, and in its 
center a small transverse tubercle. Wing-covers with fine shallow punctures in 
* Not reproduced. 
