lat-headed
Borers in Pine. _a_, work of round-headed borer, "sawyer,"
_Monohammus spiculatus_, natural size _b_, _Ergates
spiculatus_; _c_, work of flat-headed borer, _Buprestis_,
larva and adult; _d_, bark; _e_, sapwood; _f_, heartwood.]

The character of the work of this class of wood- and bark-boring grubs
is shown in Fig. 24. The injuries consist of irregular flattened or
nearly round wormhole defects in the wood, which sometimes result in
the destruction of valuable parts of the wood or bark material. The
sapwood and heartwood of recently felled trees, sawlogs, poles posts,
mine props, pulpwood and cordwood, also lumber or square timber, with
bark on the edges, and construction timber in new and old buildings,
are injured by wormhole defects, while the valuable parts of stored
oak and hemlock tanbark and certain kinds of wood are converted into
worm-dust. These injuries are caused by the young or larvae of
long-horned beetles. Those which infest the wood hatch from eggs
deposited in the outer bark of logs and like material, and the minute
grubs hatching therefrom bore into the inner bark, through which they
extend their irregular burrows, for the purpose of obtaining food from
the sap and other nutritive material found in the plant tissue. They
continue to extend and enlarge their burrows as they increase in size,
until they are nearly or quite full grown. They then enter the wood
and continue their excavations deep into the sapwood or heartwood
until they attain their normal size. They then excavate pupa cells in
which to transform into adults, which emerge from the wood through
exit holes in the surface. This class of borers is represented by a
large number of species. The adults, however, are seldom seen by the
general observer unless cut out of the wood before they have emerged.

Flat-headed Borers

The work of the flat-headed borers (Fig. 24) is only distinguished
from that of the preceding by the broad, shallow burrows, and the much
more oblong form of the exit holes. In general, the injuries are
similiar, and effect the same class of products, but they are of much
less importance. The adult forms are flattened, metallic-colored
beetles, and represent many species, of various sizes.

Timber Worms

[Illustration: Fig. 25. Work of Timber Worms in Oak. _a_,
work of oak timber worm, _Eupsalis minuta_; _b_, barked
surface;