Carpenter Ants

Carpenter ants get their name from their habit of building nests in wood. Unlike termites, they do not feed upon wood but merely use it as a place to nest. They will build their nests in homes and may cause significant structural damage. Carpenter ants are recognized by their characteristic evenly rounded thorax when viewed from the side.

The black carpenter ant, Camponotus pennsylvanicus, is the largest and most common house-infesting carpenter ant in Minnesota. Individual workers range in size from 1/4 inch to 5/8 inch in length. This species is generally totally black.

Biology & Habits

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, sub-flooring, 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.

Control

Stacks of firewood or other lumber outdoors are attractive nesting sites. Store the wood off the ground and away from the house. It is better to keep only the amount of firewood that you would use during one heating season because the longer wood is left undisturbed, the more likely it is that carpenter ants will occupy it. Spraying firewood to protect it is not safe, and is against the recommendation of most insecticide labels.

We treat the perimeter of the exterior with a non-repellant product that is undetectable by the ants. The product attaches to their bodies as they walk through it. They transfer the slow-acting product to every member of the colony as they touch each other while feeding, grooming, and communicating. Within three weeks, the ant activity should be completely under control. Rainbow Pest Experts guarantees the Carpenter Ant treatment to the following March 31.

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