TIMBER BEETLE. 
283 
It is only after timber has been felled some time 
that it is liable to be attacked by this beetle; and it 
seems that spruce fir, of all other kinds, is most to 
its taste. The female of this species is furnished 
with a flat retractile tube, which she inserts between 
the bark and the wood, to the depth of about a 
quarter of an inch, and there deposits an egg. It 
appears that she never lays more than one in a 
place. By stripping off the bark it is easy to trace 
the whole progress of the larva, from the spot 
where it was newly hatched, to that where it has 
attained its full size. At first it proceeds onwards, 
but in a serpentine direction, filling the space which 
it leaves behind it with its excrement, resembling 
saw-dust, and thus stopping all ingress to enemies 
from without. When it has arrived at its utmost 
dimensions, it does not confine itself to one direc- 
tion, but works in a kind of labyrinth, eating back- 
wards and forwards ; which gives the wood under 
the bark a very irregular surface, and considerably 
increases the width of its path. Its attacks are 
not confined to the solid timber, but in its progress 
it eats away an equal portion of the bark. The 
bed of those paths where it has been at work ex- 
hibits, when closely examined, a curious appear- 
ance, occasioned by the erosions of its jaws, which 
excavate an infinity of little ramified channels. 
When the larva prepares to assume the chrysalis 
state, it bores down obliquely into the solid wood, 
to the depth sometimes of three inches, seldom less 
