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 on top of the infested wood. The frass, which is loosely packed in the tunnels, is composed of very
line powder and tiny, elongate, blunt-ended pellets that often split lengthwise when dry. The exit
holes are oval and 1/4 to 3/8 inch in diameter. Robing the wood surface sometimes exposes the
damage. The sapwood may be completely destroyed leaving only a paper thin surface of wood.
The galleries have a rippled pattern like sand over which water has washed. In centrally heated
houses without moisture problems, the borers seldom do excessive damage. The damage is general-
ly restricted to a few boards. Serious damage occurs where enough humidity or moisture exists for
reinfestations to occur.
Buprestids, also known as the flat-headed borers or metallic beetles, are a
common type of wood borer which attacks weakened, injured, dead or dying trees and freshly cut
logs of both hardwoods and softwoods. They seldom attack dry wood. The larvae have a flattened
area behind the head and the beetles have beautiful markings and metallic colors. They are found
throughout the contiguous states and the tropics. The borer rarely emerges from within a building,
and there is no danger of serious damage to structural timbers. However, the flat-headed borer
should be recognized for the type of damage it can do before the wood is put into service.
Wood damaged by flat-headed borers has winding tunnels that are extremely flat, and three to four
or more times as wide as high. Since the wood is usually sawed after the damage has occurred, the
tunnels are often cut at an oblique angle and their cross-sections are distorted (Figure 4-25). The
tunnels are very tightly packed with layers of sawdust-like borings and pellets, and their walls are
scarred with fine, transverse lines. The frass is somewhat like that of some round-headed borers,
but the galleries are much more flattened. The tunnels of round-headed borers are no more than two
to three times broader than high, and the frass is less tightly packed.
The galleries under the bark edges left on structural timbers are serpentine and wander over the sur-
face of the outer sapwood. The borer will continue to develop, and can be heard chewing under the
bark until the wood becomes too dry. The galleries are packed with a mixture of light, wood-
colored frass and brown, bark-colored frass.
Exit holes made by the adults in the surface of the wood are sometimes present. They are elongate
to oval, much like the exit holes made by some of the flattened long-homed beetles, such as the old
house borer.
Curculionids are a family of beetles, some of which are known as the snout
beetle or wood boring weevil. These beetles are not common, do not cause significant damage, but
could be confused with anobiid beetles.
These beetles attack hardwoods and softwoods. When damage is heavy, the interior of the wood, in-
cluding sapwood and heartwood, is honeycombed (Figure 4-26). They may be distinguished from
the other beetles by the prolongation of the head into a snout.
Scolytids are known as bark beetles or engraver beetles, and range throughout
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