_c_, bark; _d_, sapwood timber worm, _Hylocoetus
lugubris_, and work; _e_, sapwood.]

The character of the work done by this class is shown in Fig. 25. The
injury consists of pinhole defects in the sapwood and heartwood of
felled trees, sawlogs and like material which have been left in the
woods or in piles in the open for several months during the warmer
seasons. Stave and shingle bolts and closely piled oak lumber and
square timbers also suffer from injury of this kind. These injuries
are made by elongate, slender worms or larvae, which hatch from eggs
deposited by the adult beetles in the outer bark, or, where there is
no bark, just beneath the surface of the wood. At first the young
larvae bore almost invisible holes for a long distance through the
sapwood and heartwood, but as they increase in size the same holes are
enlarged and extended until the larvae have attained their full
growth. They then transform to adults, and emerge through the enlarged
entrance burrows. The work of these timber worms is distinguished from
that of the timber beetles by the greater variation in the size of
holes in the same piece of wood, also by the fact that they are not
branched from a single entrance or gallery, as are those made by the
beetles.

[Illustration: Fig. 26. Work of Powder Post Beetle,
_Sinoxylon basilare_, in Hickory Poles, showing Transverse
Egg Galleries excavated by the Adult, _a_, entrance; _b_,
gallery; _c_, adult.]

[Illustration: Fig. 27. Work of Powder
Post Beetle, _Sinoxylon basilare_, in Hickory Pole. _a_,
character of work by larvae; _b_, exit holes made by
emerging broods.]

Powder Post Borers

The character of the work of this class of insects is shown in Figs.
26, 27, and 28. The injury consists of closely placed burrows, packed
with borings, or a completely destroyed or powdered condition of the
wood of seasoned products, such as lumber, crude and finished handle
and wagon stock, cooperage and wooden truss hoops, furniture, and
inside finish woodwork, in old buildings, as well as in many other
crude or finished and utilized woods. This is the work of both the
adults and young stages of some species, or of the larval stage alone
of others. In the former, the adult beetles deposit their eggs in
burrows or galleries excavated for the purpose, as in Figs. 26 and 27,
while in the latter (Fig. 28) the eggs are on or beneath the surface
of