Old House Borer

The Old House Borer is one of the most common wood destroying beetle, with it’s larvae hollowing out galleries in seasoned softwood(pine). It is found in older buildings, but is more frequent in newer buildings,(in houses less than 10 years old).The adults are brownish-black to black, slightly flattened and about 3/4-1 inch long.


The average life cycle is usually one to three years but can take up to twelve years if nutritional and environmental conditions are unfavorable. Because of the long life cycle, it may take years before you see any structural damage .


The exit holes are about 1/4-3/8-inch in diameter, but damage may have occurred for several years before spotting such holes. They can digest cellulose.


When wood has been infested with fungi, the larval development is faster. Their powder (frass) in the tunnels are like tightly packed sawdust.

Control Measures

♦  Prevention. Most beetle problems are introduced into homes in lumber or finished wood products (i.e., 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. 

♦  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.

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