Carpenter Ants found in the summer are often invaders wandering in from outdoors, but since carpenter ants, like all insects, are cold blooded, ants active in the winter must be originating from a warmed source. Even if the air temperature is very cold, heat from the sun or the furnace may warm house walls and stir dormant ants to activity.
Large colonies of black carpenter ants consist of a “parent” colony in a dead log or stump, with various “satellite” colonies occupying other pieces of wood somewhere nearby. The parent colony contains the egg-laying queen, whereas the satellite colonies contain workers, larvae and pupae only. Mature colonies produce winged ants. Winged ants disperse away from the mature colony to start new colonies. Most winged ants develop during late summer, spend the winter in the nest, and swarm the next spring. After swarming and mating, winged females drop to the ground, chew off their wings, and begin establishing new colonies. Immediately following mating, male winged carpenter ants perish and play no part in establishing a new colony.
Carpenter ants may become household pests by foraging for food indoors. The diet of carpenter ants includes living and dead insects, meat, fats and sweets of all kinds, including honeydew from aphids and nectar from plants. Foraging workers collect all the food for the colony and may travel up to 100 yards from the nest in search of food. Foraging activity is highest at night. Solitary ants seen during the day are usually scouts. Liquid food is ingested by ant workers and then regurgitated to other ants in the colony at a later time. Worker ants cannot eat solid food and must carry it back to the nest and feed it to the larvae. The larvae process the solid food and regurgitate it back to the other ants in liquid form.
Carpenter ants normally construct their nests in hollow trees, logs, posts and landscaping timbers. They prefer to nest in wood that is moist and rotting or that has been hollowed out by decay or by other wood-destroying organisms. Carpenter ants remove wood in the form of a coarse sawdust-like material, which they push from the nest. This often results in a cone-shaped pile accumulating just below the nest entrance hole. This pile may include other debris from the nest, including bits of soil, dead ants, insect parts and other food remnants. They cut galleries along the grain of the wood, preferring the softer spring grain. They leave the harder summer grain, which serves as walls separating the tunnels. They cut openings in these walls to allow access between tunnels. Carpenter ants keep their galleries clean; the tunnels look smooth as if sanded. (See below.)
The greatest concern with carpenter ants is that they will establish satellite nests in structural wood. This can cause serious damage. They will establish these nests in areas such as the roof trim, siding, rafters, joists, sheathing, decks, porches, steps, sills, subflooring, doors and window frames. They may also establish nests inside hollow areas, like hollow doors or small voids produced during construction. Most often, they establish nests in areas of the structure where the wood is moist or has been damaged by moisture. They can also move from decaying portions of the wood into sound lumber in the process of enlarging the nest.