Carpenter ants are a common pest of homes and buildings. They are big bodied and range from black to black and red. There are two species of carpenter ants (C. modoc & C. vicinus) that cause problems for home and building owners in the Pacific Northwest. Both occur naturally in live or dead trees and stumps (video), in wood buried in the soil or under rocks and in landscape timbers. Nests are usually associated with moisture. Carpenter ants become pests of economic importance when they invade homes and buildings. Damage is due to the smooth galleries excavated in wood.
Carpenter ant satellite colonies are typically established in homes from a main colony somewhere on the property. Satellites can be found in a variety of situations including wood that is stressed from moisture, wall voids, cavities, hollow doors, under insulation, in roofing material (particularly styrofoam insulation) or in undisturbed areas in attics or crawlspaces. Ants continually move back and forth between satellites and main colonies along trails. They also establish foraging trails in search of food. Foraging ants are most easily discovered at night during their peak activity. Carpenter ants are polymorphic (vary in size) and exhibit characteristic “swarming” behavior in the spring when winged reproductives can occur in the hundreds. Carpenter ants can be detected by the appearance of winged swarmers or faraging workers, by the tell tale piles of sawdust from their excavations or by “scratching” sounds in the wall.