Carpenter ants are very large ants. They make their nests in wood, but they do not eat the wood. Outdoors they nest in trees, fallen logs, and rotting stumps. The workers gather insects and honeydew for the colony to eat.
If food or water becomes hard to find, the carpenter ant colony might invade homes. If they find food, the workers often make a nest inside the house. The workers frequently make the nest in an area that is near the food or water supply. In these cases, the workers make nests in attics, in wall voids, and even inside of hollow doors.
Carpenter ants have been found nesting in the foam sheathing that is used in building homes. The ants excavate the foam to make their galleries. Homeowners find small pieces of foam on the ground beside the foundation around the outside of the home.
If there is wood that is decaying because of dampness, the carpenter ants will choose it for their nesting site. Scientists suspect that the ants choose decaying wood because it is easier for them to hollow out than dry, solid wood. Homeowners find carpenter ants nesting in damp, decaying wood in eaves, crawl spaces, bathroom walls, window or door frames, and under roof shingles.
Depending on the location of the nest, homeowners sometimes report hearing carpenter ants moving around. The sound that the homeowners report hearing is a rustling that comes from ant nests inside of walls or other void spaces.
When carpenter ants make nests in wood, they hollow out chambers in the wood. Termites fill their galleries with dirt, but here is no dirt in carpenter ant galleries. The carpenter ant workers make the sides of the galleries so smooth that they seem to be sanded. If carpenter ants are allowed to work undisturbed, they can cause considerable damage to the wood in a home.
As the workers create the galleries, they make piles of debris. The debris looks like wood shavings. They push the debris out of the galleries along with the remains of insects that the ants have eaten. Homeowners find the debris and dead insects piled up on windowsills or floors. The piles of debris are often the first clue that there is a carpenter ant problem.