Carpenter ants are so-named because these social insects excavate galleries in wood to create nest sites. They use their strong jaws (mandibles) to remove quantities of wood as they expand the size of their nests. Unlike termites, carpenter ants do not consume wood.

Carpenter ants are among the largest ants occurring in the United States, and some species are about ½ inch long. Carpenter ants are social insects and live in colonies made of different forms of ants or “castes.” Workers of several sizes occur in a single colony. These polymorphic workers are sometimes called minor, intermediate, and major workers (smallest to largest respectively).

Carpenter ants may be black, red, brown, tan, yellow, or some combination thereof, depending on the species. The Black carpenter ant, Camponotus pennsylvanicus, is the most common species in the Northeast. This ant is black, with very fine whitish or yellowish hairs on the abdomen.

Winged male and female carpenter ants (swarmers) emerge from mature colonies usually from March to July. After mating, the males die and each newly fertilized female establishes a new colony in a small cavity in wood, under bark, etc. The first brood of larvae is fed entirely by the queen.

The few workers emerging from the first brood assume duties of the colony, such as collecting food (the carpenter ant diet consists of a wide range of plant and animal materials), excavating galleries to enlarge the nest, and tending the eggs and larvae. All of the workers are sterile females.

Mouthparts are for chewing. They are capable of biting, but they do not sting. These ants usually nest in dead wood, either outdoors in old stumps and dead parts of trees and around homes (in fences, fire wood, etc.) or indoors (between wood shingles, in siding, beams, joists, etc.). Nests can be located by searching for piles of sawdust-like wood scrapings and feces (frass) underneath exit holes. These piles accumulate as the nests are excavated and usually also contain parts of dead colony members.