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Powderpost
Beetle Infestations
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Typical infestations of wood boring beetles
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Summary: Wood
boring powderpost beetle infestations occur in
both softwoods and hardwoods. Softwood
infestations typically occur in structural
wood like beams and joists while hardwood
infestations occur in flooring, furniture
and cabinets.
Jack DeAngelis, PhD
OSU Ext. Entomologist
(ret.)
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Beetle infestations in softwood and
hardwood
Powderpost beetles,sometimes
called woodworms, are wood boring beetles that
infest both softwoods
like pine, fir, spruce and hardwoods
like oak, maple, and ash. Unlike most other
insects that damage wood (see Wood
Destroying Insects), powderpost beetles have
the potential to start a cycle of infestation
that may last many years and do significant damage
to the wood they infest.
Infestations of these beetles can have
serious economic impact. Significant damage to hardwood
flooring and cabinets can occur as
well as weakening of structural timbers like posts,
floor joists, subfloors, and other
framing materials. Suspect infestations can
also interfere with real estate transactions even
if the beetles are no longer active.
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Lyctid powderpost beetle
emergence holes in the face frame of a
kitchen cabinet (look carefully below the
shadow).
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Some examples of powderpost beetle
infestations
Infestations usually come in one of two
varieties: infestations in softwood structural
timbers like floor joists, posts, beams, or,
infestations of hardwoods such as flooring,
furniture or cabinets. The following examples
illustrate some fairly typical situations.
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Scenario 1: Beetle
infestations in structural wood affecting
sale of home
- During
a pest and dry-rot inspection of a newly
renovated house powderpost beetle emergence
holes and fresh boring dust are found in some
structural timbers in the crawl space under
the house. The home inspector reports this to
the potential buyers who promptly pull out
of the transaction because they are
afraid of the beetle infestation. The
homeowners want to know if the infestation is
active and how to treat it so they can get the
house back on the market.
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- Options: Structural wood like
softwood beams and posts can be treated with a
borate-based wood preservative such as Bora-Care
that will prevent re-infestation. Larvae that
are still developing inside the wood are
difficult or even impossible to treat but the
borate treatment will disrupt the infestation
when these larvae emerge as adults.
Insecticides to treat powderpost
beetle infestations
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Scenario 2: Beetle
infestation found in hardwood cabinets,
owner threatens to sue cabinet maker
- A cabinet maker is faced with
replacing the kitchen cabinets in 40
apartments because the wood frames made of the
hardwood poplar show the characteristic signs
of a powderpost beetle infestation (emergence
holes and powder or boring dust, see image
above). The primary concern is "will emerging
beetles be a threat to other wood in the
apartments?"
- Options: Other nearby hardwoods
will not be attractive to emerging beetles if
they are varnished
or painted.
However, new, unfinished wood can become
infested so it should be treated with a
borate-based insecticide such as Bora-Care
or Timbor. Both
materials are water-based and can be simply
"painted" on these surfaces where the borate is
absorbed into the wood.
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Scenario 3: Beetle
infestation found in hardwood flooring.
Where did it come from, when did it start?
- Hardwood flooring is sometimes
infested with lyctid powderpost beetles
that begin to emerge a few years after the
flooring is installed. Emerging beetles leave
behind holes and "frass" or small piles of boring dust made
of fine wood fragments. Concerns range from
"do the beetles pose a threat to other wood in
the home?" (see scenario
2 above) to "when did the wood
become infested and therefore who is legally
responsible?" and, "how much damage will
eventually occur?".
- Options: This situation is the
most complex of the three scenarios. The
question "when/where did it start" largely
depends on when the floor was installed and the
rate of beetle emergence. Infestations typically
begin at the manufacturing plant even if the
stock wood was kiln-dried. Stock that is not
stored properly can become infested if exposed
to a nearby active infestation. Emergence of the
subsequent infestation can occur over several
years following installation. See Related
Articles below for various control
options.
What
are Powderpost Beetles?
Powderpost Beetle
Control & Prevention
Powderpost Beetle
Damage in Hardwood Flooring & Furniture
Using Bora-Care
& Shell-Guard Wood Preservatives
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