Household Wood-boring Insects
Wood-boring beetle larvae feed on wood and wood products; adults emerge from larval feeding chambers through round, oblong, or D-shaped exit holes. Adults of some species also bore holes into plaster, plastic, and soft metals.
Three families of beetles have species of wood borers that invade and damage structural and decorative wood and furniture. These families are the powderpost beetles, deathwatch beetles, and false powderpost beetles.
IDENTIFICATION AND LIFE CYCLES
Powderpost Beetles
Beetles in the family Lyctidae are known as powderpost beetles. They are so named because
larvae leave a fine, dustlike powdered frass (a mixture of feces and food fragments) in
their galleries that occasionally falls out of exit holes into small piles on floors or
other surfaces. This powdered frass is characteristic of powderpost beetles and helps
distinguish them from other typical wood-boring beetles. Lyctids attack hardwoods
apparently because these woods have pores into which they can lay eggs; softwoods do not
have such pores. Also, the starch content in softwoods is nutritionally low for these
beetles. They will attack woods that are very dry (as low as 8 percent moisture).
Woods most often attacked by this beetle are oak, ash, hickory, mahogany, and walnut; infestations are most likely to occur in wood paneling, molding, window/door frames, plywood, hardwood floors, bamboo articles, and furniture. Infestations may occur if beetles or larvae are brought into a building in furniture or firewood. Sometimes the only sign of infestation may be the tiny, round exit holes made by emerging adult beetles. Once they emerge, the winged adult beetles spread to other wood surfaces where they deposit eggs onto unfinished surfaces or in cracks or other openings. They have a life cycle ranging from 3 months to over 1 year, depending on temperature, humidity, and the nutritional quality of the wood.
Deathwatch Beetles
Wood-boring beetles in the family Anobiidae are known as deathwatch beetles. Deathwatch
beetles are closely related to the drugstore beetles, which are stored product pests.
Adults communicate with each other and probably locate mates by tapping their heads
against wood, usually at night. (Deathwatch beetles supposedly acquired their name during
medieval European times from people who heard the tapping while sitting up with a sick or
dying person during the night.) Deathwatch beetles are found primarily in soft woods,
including girders, beams, foundation timbers, and some types of furniture. Some species
attack books. This beetle is typically found in old wood and may be associated with wood
that is partially decayed.
False Powderpost Beetles
Wood-boring beetles in the family Bostrichidae are sometimes known as false powderpost
beetles. Larvae tightly pack their galleries with frass that has the consistency of coarse
powder; this coarse texture distinguishes them from true powderpost beetles as well as the
deathwatch.
MANAGEMENT
Wood-boring beetles are difficult to control once an infestation has begun. Prevention is
the best management method, and protective measures should be taken at every stage of
lumber processing and handling including lumber mills, plywood mills, lumber yards,
furniture manufacturing factories, and building construction firms. Sanitation is the most
important aspect of prevention. Remove and destroy dead tree limbs around buildings or
near any area where wood products are stored. Destroy scrap lumber and other wood products
before they become infested. Kiln drying of lumber destroys beetle infestations, although
it does not prevent reinfestation. Materials used for construction of buildings and wood
furniture should be thoroughly inspected before use to be certain that they do not contain
wood-boring beetles. Protect wood from infestation by painting or varnishing to seal
pores, cracks, and holes where eggs could be laid.
To keep from accidentally introducing wood borers, inspect furniture and other objects before bringing them into buildings. Fumigate objects that show signs of beetle infestation. When bringing in firewood, only bring in what will be burned that day. Also, inspect the building for signs of wood borer damage. Look for exit holes where adult beetles have emerged. Once galleries have been located, tap out frass to aid in identifying the pest.
Small wooden items (but not those containing fabrics, pelts, or paints) can be heated in an oven at 120 to 140°F (49 to 60°C) for 6 hours or placed in a deep freeze at 0°F (-18°C) for 72 hours. Longer treatments may be required if the wood is thicker than 2 inches.
Remove and replace infested structural wood whenever possible to eliminate beetles. Destroy infested wood by burning or take it to a landfill area. Where removal is not possible, use liquid insecticides containing materials such as chlorpyrifos, permethrin, cypermethrin, or cyfluthrin that are labeled for the control of these pests. Apply the insecticide only to infested areas, but be sure these are thoroughly soaked. Remove and have infested furniture fumigated. Extensive infestations within a building, or where inaccessible structural parts of a building are involved, may require whole-building fumigation by a professional pesticide applicator. Whenever applying dusts, liquid insecticides, or fumigants, be sure to follow label instructions carefully. Wear the required protective clothing and respiratory equipment.