Powderpost Beetles and Other Wood-Infesting Insects1
P. G. Koehler and F. M. Oi
Powderpost beetles can be serious pests of structures . The
larvae of these beetles live in and consume dry, seasoned wood. The most
common types of powderpost beetles are Anobiid, Lyctid, and
Bostrichid beetles. Other wood infesting pests are oldhouse borers and
carpenter bees. This publication explains how to recognize powderpost beetles
and other wood-infesting pests as well as their damage to wooden structures
(Table 1 ).
Anobiid Powderpost Beetles
Anobiid powderpost beetles ( Figure 1 ) are usually about 1/16 to 1/4 inch
long, reddish brown or grayish brown to dark brown. The body is cylindrical,
elongated and covered with fine hair. The head is covered by pronotum from top
view; the last 3 segments of antennae are usually lengthened and broadened.
The larvae are white, "C" shaped grubs with rows of small spines on dorsal
side ( Figure 2 ). The beetles' life cycle lasts 1 to 10 years depending on
the species. Anobiid powderpost beetles infest seasoned softwood and the
sapwood of seasoned hardwoods.
CREDITS: James Castner, University of FloridaFigure 1. Anobiid powderpost beetle.
CREDITS: University of Florida
Figure 2. Deathwatch beetle (Anobiidae).
Most commonly, infestations of Anobiid powderpost beetles are found in
structural timbers made of softwood, such as beams, sills, joists, studs,
subflooring, and plywood. In addition, Anobiids will infest hardwood
furniture, wall paneling, window and door molding, hardwood floors, and
furniture. Woods such as maple, beech, poplar, and pine are especially
susceptible to attack. They prefer to infest wood with high moisture content
in poorly ventilated areas in crawl spaces of houses, utility rooms, and
garages. Under favorable conditions, the infestation then spreads into walls
and other areas of the structure. Infestations develop slowly but wood can be
reinfested year after year.
Signs of Infestation
The key to avoidiing serious problems with Anobiid powderpost beetles is
early detection and control. Usually, homeowners see the damage rather than
the beetles. The larval damage occurs entirely below the surface of the wood
where larvae eat tunnels. This damage is not usually seen until the wood
disintegrates. However, the adults emerge from the wood leaving emergence
holes and powder-like frass that sifts from the holes.
Emergence holes from Anobiids are 1/16 to 1/8 inch in diameter, round in
shape. Cigar-shaped frass is found loosely in tunnels and in small mounds
outside of emergence holes. The frass is powderlike but feels gritty to the
touch.
Bostrichid Powderpost Beetles
Bostrichid powderpost beetles ( Figure 3 ) are 1/8 to 3/4 inch long,
reddish brown to black in color. Their bodies are elongated and cylindrical
with a roughened thorax. Heads are concealed by the pronotum from above; the
antennae are short with 3 or 4 enlarged sawtoothed terminal segments. The
larva is white, "C" shaped with no spines on body ( Figure 4 ). The life cycle
is 1 year. Bostrichids infest seasoned softwood and hardwood; especially
unfinished floors, window sills, furniture, etc. Bamboo items are especially
susceptible to attack by some species of Bostrichid beetles.
CREDITS: James Castner, University of Florida
Figure 3. Bostrichid powderpost beetle.
CREDITS: University of Florida
Figure 4. Bamboo borer (Bostrichidae).
Signs of Infestation
The round emergence holes are 1/8 to 3/16 inch in diameter. Sawdust-like
frass sticks together and is found tightly packed in galleries but not in
entrance holes.
Lyctid Powderpost Beetles
Lyctid powderpost beetles ( Figure 5 ) are about 1/4 inch long, brown in
color, body elongated and slightly flattened, prominent head not covered by
pronotum, and antennae with a 2-segmented terminal club. The larvae are white,
"C" shaped, with 8th abdominal spiracle enlarged ( Figure 6 ). This beetle's
life cycle is 6 months to 4 years.
CREDITS: James Castner, University of Florida
Figure 5. Lyctid powderpost beetle
.
CREDITS: University of Florida
Figure 6. Powderpost beetle (Lyctidae).
Lyctids infest the sapwoods of hardwoods; mainly ash, hickory, oak, maple,
and mahogany. Consequently, most infestations are found in wood paneling,
molding, window and door frames, hardwood floors, and furniture. Imported
tropical hardwoods are especially infested with Lyctids because of poor
storage and drying practices prior to shipment to the U.S. Joists, rafters,
and subfloors of houses are not usually infested with Lyctids because they are
usually made of pine or other softwoods.
Lyctids rarely infest wood older than 5 years. Therefore, infestations are
usually in new homes or newly manufactured articles. Infestation usually
results from wood that contained eggs or larvae at the time of purchase.
Typically the item was made from wood that was improperly dried or stored.
Old House Borer
The larvae of the old house borer (a long-horned wood boring beetle -
Cerambycid) ( Figure 7 ) sometimes infest softwoods in Florida. The adult
beetle is grayish-black, 1/2 to 3/4 inch in length with several white markings
on the wing covers and long antennae. The female lays eggs in crevices of logs
or timbers. The larvae hatch and require 3 to 5 years or more to mature. The
larvae are 1/2 to 1 1/2 inches long and are white, segmented and have an
enlarged, brownish head (Figure 8 ). They bore through the wood making
irregular galleries. During quiet times, their feeding may be heard as a
clicking or rasping sound. The beetles emerge through an oval hole about 1/4
to 3/8 inch in diameter
. 
CREDITS: James Castner, University of Florida
Figure 7. Old house borer adult.
CREDITS: University of Florida
Figure 8. Old house borer (Cerambycidae).
Signs of Infestation
The key to avoiding serious problems with old house borers is early
detection and control. Usually, homeowners see the damage rather than the
beetles. The larval damage occurs entirely below the surface of the wood where
larvae eat tunnels. However, their frass occupies more space than the volume
of wood that is consumed. Therefore, they fill the tunnels in the wood
completely causing a blistering or rippled effect. The frass is a fine,
powder-like dust that is found loosely packed in tunnels and in small piles
outside of the hole. The frass is extremely fine and feels like talc but
usually has small pellets of frass mixed with it. Adult emergence holes are
oval and 1/4 to 3/8 inch in diameter.
Control of Anobiid, Bostrichid, and Lyctid Powderpost Beetles and Old
House Borers
There are several options for control of powderpost beetles and old house
borers. Selecting the best option depends on a number of factors, such as the
severity of infestation, the location of infestation, potential for
reinfestation, and cost of treatment. Powderpost beetles and old house borers
damage wood slowly so there is plenty of time to make a decision on control
options.
* Prevention. Most beetle problems are introduced into homes in lumber
or finished wood products (e.g., furniture, paneling, or flooring). Most
serious infestations occur when infested wood is installed in the house.
Inspect wood to insure that wood is not infested at the time of home
construction.
* Wood finishes. Powderpost beetles only lay eggs on bare, unfinished
wood. Beetles will not infest wood that is painted, varnished, waxed, or
similarly sealed. Beetles emerging from painted or varnished wood were either
in the wood before finishing or were a result of reinfestation by eggs that
were laid in emergence holes of adult beetles. Sealing holes prevents
reinfestation from eggs laid within the hole.
* Wood replacement. Infested wood can be replaced if the infestation
appears to be localized. For instance, if emergence holes appear in a member
of a door or window frame, the piece can be removed and replaced with a new,
uninfested wood.
* Surface treatment. Insecticides are labeled for surface treatment of
bare, exposed wood. Spraying or brushing insecticides onto infested wood
creates a barrier that kills adult beetles as they chew their way out of wood.
The barrier also kills newly-hatched larvae as they attempt to bore into wood.
For the surface treatments to work properly, they must penetrate the wood.
Therefore, the wood should be unfinished or sanded to remove the finish. In
certain situations, the surface treatment can penetrate the wood sufficiently
to kill larvae within the wood to prevent the further marring of the surface
by additional emergence holes of adults. Insecticide labels for wood surface
treatment are listed in Table 2 . Because most unfinished wood is in either
voids or attics, products registered for treatment of wood in attics and voids
are listed in Table 3 .
* Fumigation. Fumigation is considered the most effective method of
controlling wood-boring beetles. However, fumigation can be the most costly
method of control and does not provide residual protection of the wood. Only
pest control operators certified to apply fumigants can do fumigation work.
Fumigation of infested furniture or small articles like picture frames and
baskets can be done without fumigating the entire structure. Some pest control
operators will fumigate infested furniture inside fumigation chambers at their
business so that the entire building does not need to be tented and fumigated.
Products registered for fumigation are listed in Table 4 .
Carpenter Bees
Carpenter bees (Figure 9 ) are 3/4 to 1 inch long and closely resemble
bumble bees except that their abdomen is a shiny metallic greenish-black;
whereas, the abdomen of bumble bees is very hairy. These insects sometimes
build their nests in solid wood such as weather boarding, railings, supports,
and trim of buildings. Their nests are in the form of tunnels 3 to 6 inches
deep in the wood. The entrance hole is about 1/2 inch in diameter. The holes
are very clean and appear as though they were made by a drill. Damage to wood
is seldom extensive
.
CREDITS: Paul M. Choate, University of Florida
Figure 9. Adult carpenter bee, Xylocopa sp.
Control
Carpenter bees can be controlled by removing and replacing infested wood.
Painting, staining, or filling holes with putty does not usually prevent the
bees from digging a new tunnel.
Insecticides can be used to treat areas of wood where carpenter bees are
active. Table 2 lists products that can be used to treat wood for carpenter
bee management.
Classification of families of beetles which attack wood.
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This document is copyrighted by the University of Florida, Institute of
Food and Agricultural Sciences (UF/IFAS) for the people of the State of
Florida. UF/IFAS retains all rights under all conventions, but permits free
reproduction by all agents and offices of the Cooperative Extension Service
and the people of the State of Florida. Permission is granted to others to use
these materials in part or in full for educational purposes, provided that
full credit is given to the UF/IFAS, citing the publication, its source, and
date of publication.11/29/04
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