Occupied galleries are kept immaculate. Shredded wood fragments from the excavations are carried from the nest and deposited outside. The piles may also contain inedible portions of insects, bits of oil and sand, empty coats, and general debris. Unlike termite tunnels, the walls of a carpenter ant nest, which have a sandpaper appearance,actually are smooth and clean. Nests usually begin in soft, decaying wood while subsequent excavations are frequently made into sound, dry lumber.
Carpenter ants are omnivorous.
Their diets include a great variety of both animal foods and plant foods, but they don't eat and digest wood as termites do. Honeydew from aphids, scale insects and other plant-sucking insects provides much of their sweet food. The ants congregate around groups of these insects and collect secreted honeydew. Carpenter ants feed on other types of insects, but the aphids usually are not harmed. Indeed, they are even protected in some cases.