Carpenter ants burrow into wood to make nests, but do not feed on the wood.They commonly nest in dead portions of standing trees, stumps, logs, and sometimes wood in houses. Normally they do not cause extensive structural damage. Most species start their nests in moist wood that has begun to decay. They attack both hardwoods and softwoods.

The most obvious sign of infestation is the large reddish-brown to black ants, 6 to 13mm long, inside the house. Damage occurs in the interior of the wood. There may be piles or scattered bits of wood powder (frass), which are very fibrous and sawdust-like. If the frass is from decayed wood, pieces tend to be darker and more square ended. The frass is expelled from cracks and crevices, or from slit-like openings made in the wood by the ants. It is often found in basements, dark closets, attics, under porches, and in crawl spaces. Galleries in the wood extend along the grain and around the annual rings.

The softer spring wood is removed first. The surfaces of the galleries are smooth, as if they had been sand papered, and are clean. The most effective way to control carpenter ants is to locate the nest and kill the queen in colonies in and near the house with insecticides. It is sometimes also helpful to treat the voids in walls.