POWDER-POST BEETLES

A, Section through plate and stud infested by borers; a, galleries packed with frass as would normally be found; b, galleries, frass removed; c, larva (nearly natural size). B, Life stages (about twice natural size); d, adult; e, larva; and f. pupa.

POWDER-POST BEETLES

Powder-post beetles attack the woodwork of buildings and reduce the wood to a powderlike condition. One of them is the old house borer. Powder-post beetles cause extensive damage in this country in sills, floor joists, studs, door jambs, flooring, siding, and rafters of buildings.

Some powder-post beetles infest only the sapwood portion of flooring made of seasoned hardwoods, such as oak or maple. Others attack the sapwood of such soft woods as pine, fir, and hemlock used for the under structure and roofs of buildings. Some infest only wood with the bark still intact the females lay their eggs in crevices on the surface of the bark or deposit them in the inner bark through slits they make. Some deposit their eggs in pores or crevices in wood devoid of bark. Others bore holes directly into the wood and place their eggs in tunnels.

Wood infested by powder-post beetles can be detected readily by the presence of powder or pellets coming from holes leading to the surface. Sometimes also one can hear rasping or scratching sounds made by grubs of the beetles as they cut channels through the wood. Little or no powder may be observed then on the surface of the infested wood. By probing with a sharp-pointed instrument, however, one can detect the powder at once. Such activity is characteristic of the old house borer, an introduced pest that is becoming well established in many buildings in this country. Frequently lumber is infested by this insect before it is used in construction. Such attacks are difficult to locate at the time the house is built.

Most powder-post beetles mature in a year's time. The old house borer takes 3 to 7 years. It is confined largely to the eastern half of the United States, but most of the others are generally distributed over the country.

Control: Replace with sound material all wood so badly damaged as to impair its structural strength. Wood lightly infested may be sprayed heavily or brush-coated with a penetrating insecticide, such as a 5 percent solution of pentachlorophenol. For best results make two or three applications in order to permit the chemical to be carried into the wood. Also effective for short periods are straight kerosene and a mixture of 9 parts of turpentine to 1 part of kerosene.

The best way to control severe infestations, especially in wood behind plaster-covered walls or in detached houses, is by fumigation with lethal gases. A good fumigant is hydrocyanic acid, but because of the great danger involved in its use only licensed fumigators should apply it.

Pentachlorophenol is irritating to some persons and it should be handled carefully. If it comes in contact with the body, wash it off shortly afterward with warm, soapy-water. It should not be used near an open flame.