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Wood boring beetles are a  major
cause of structural damage in homes and other structures. They can
attack hardwoods and softwoods depending on the variety. Often,
they are referred to as "power post beetles", athough three separate
families of beetles (lyctids, anobiids, and old house borers) are
responsible for most of the beetle damage to structural wood. When
not identified otherwise, the term powder post beetles usually refers
to lyctid powderpost beetles. The beetles are usually not seen,
however their exit holes can be observed by the trained eye.
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Lyctid powder post beetles infest hardwoods
and can be found in manufactured products in relatively new homes.
They can be introduced as eggs or larvae in firewood, improperly dried
wood, or even wood that has been stored. Hardwood flooring, furniture,
door and window frames and decorative trim are particularly susceptible
to attack. Their short life cycle, large initial populations, and
high survival rate often result in rapid and expensive damage. The
larvae are responsible for all damage and feed entirely within the
wood. Most infestations are not discovered until adult beetles emerge
through the wood surface. The emergence holes are round, 1/32" to
1/8" in diameter. The frass is loosely packed with the feel of talcum
powder, leading to the common name of powder-post beetle.
Lyctid powder-post beetles will attack wood with moisture levels of
eight to thirty-two percent but prefer a range of ten to twenty percent,
typical of that found in most homes. The greatest period of activity
occurs in late winter or early spring. The adults hide themselves
in cracks and holes in the wood during the day and become active at
night. They are strong fliers and may be attracted to lights. Indoors,
they may be seen crawling on window sills, floors, furniture and other
surfaces. |
 Anobiid
powder post beetles attack both hardwoods and softwoods. Anobiid
exit holes are round and about 1/8" diameter. Larvae feeding in softwoods
produce numerous oval pellets which have a gritty feel. Infestations
usually begin in crawlspaces or other areas where wood is near the
ground. High moisture levels in the wood will speed the development
of these beetles and, under favorable conditions, the cycle of re-infestation
can occur within one to two years. Damage is usually detected in homes
older than ten years since infestations develop slowly. Adult beetles
are active only at night and may become numerous in early to late
spring. If an active infestation is found in a 15 to 20 year old building,
all wood should be carefully inspected for signs of infestation. This
is especially important for structures on poorly drained sites or
in warm humid climates. Exit holes indicate that adult beetles have
emerged and will continue to re-infest unless controlled. |
 In
some areas of the country, the old house borer or Cerambycid
powder post beetle is second only to termites in damage to structural
wood. They are found from Maine to Florida and west to Michigan and
Texas. Old house borers prefer to attack recently seasoned wood and
are typically found in newer homes. Infestations are often introduced
in firewood or through the use of lumber that contains eggs or small
larvae. Usually, noticeable infestations are limited to a few wood
members, however, adjoining sound boards may also be infested by young
larvae. Depending on conditions, damage may not be detected until
adults emerge three to ten years after the initial infestation. Old
house borers prefer dry wood containing ten to twelve percent moisture
content. Both the adult exit holes and the feeding tunnels of large
larvae are oval and about ¼" in diameter. Galleries near the surface
cause lighter colored streaks to appear on the wood surface. The frass
is a coarse, tightly packed powder. One typical characteristic of
an old house borer infestation is the noise older larvae make while
feeding. Often this chewing noise is what will first alert the homeowner
that an infestation is present. |
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Treatment & Control
Treatment for beetle infestations can include a combination of spraying
, brushing, and fogging. In addition moisture control remediation
should be instituted. Leaky plumbing and drain spouts should always
be repaired in addition to treatment. Wet crawlspaces should be
vented and plastic sheeting installed. Structural wood members that
are no longer sound must be replaced. Other preventative treatments
can be suggested by the inspector.
The time required to completely eliminate a beetle infestation
is influenced by factors such as the time of year treatment is performed,
beetle species, degree and age of the infestation, the wood species,
moisture content, wood thickness, and application technique. Older
larvae of species such as old house borers are more resistant and
must ingest a large quantity of the treated wood to be killed. Since
some of the older larvae can take several years to mature and eat
very little wood, they may be able to pupate and emerge several
months after treatment. This normally occurs only in logs or large
beams.
Any beetles which do emerge cannot re-infest treated wood and their
life cycle is broken at that point. Isolated beetle activity evident
after treatment may be located and eliminated using localized injection
techniques. Treatment applications during late fall and winter have
limited immediate effect on mortality. When the larvae become active
again in the spring, they will ingest the treated wood, causing
death. Complete elimination of large beetles such as old house borers
may require several months to a year.
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(860) 582-9242 Fax: (860) 582-8487