Old House Borer

The old house borer is an important pest of structural and ornamental wood around the world. The larval stage feeds on seasoned (moisture content 10 to 20 percent) softwood timber, preferring the sapwood portions of pine, fir, and spruce. Larvae will not live in rotten wood, and the oils and resins of the heartwood portion of the wood make it undesirable. They generally infest wood that is less than 10 years of age. Larvae can feed for several years in seasoned softwood, and cause cosmetic and structural damage to infested material.

The adult beetle is 5/8 to 1 inch long, slightly flattened and black to brownish-black (see figure below). The region behind the head is rounded and with two shiny areas on each side. The wing covers may be completely black or with patches of gray that form distinct bands. The larva (see figure below) is cream colored; the mandibles are dark brown. Full grown larvae may be 1-1/4 inches long. There are three distinct, dark colored eye spots on each side of the head. The old house borer spends two to ten years of its life in the larval stage. Chewing sounds can sometimes be heard as the larvae feed on the wood.