The ants are called “carpenter ants” not because they build from wood, but because of the material called “frass” that they leave behind as they destroy wood. Frass resembles sawdust, which results from gnawing away at wood to create tunnels and “galleries” to nest in. They do not eat wood, but chew it to provide nesting sites.
Carpenter ants are often found where wood touches the ground causing the wood to rot. They are attracted to moist wood and are often found under porches, windowsills and under sinks. They enter buildings around doors, window frames, plumbing and utility lines, and via shrubs and trees branches that touch buildings. Most activity takes place dusk to dawn, but some ant workers are busy during the day. The first indication of an indoor colony is a rustling sound coming from voids in walls or the emergence of “swarmers” or “worker ants” indoors. The only external indication of infestation, other than the presence of workers, are small openings on the surface of wood where the workers expel debris consisting of frass, fragments of insulation, and insect body parts.
Outdoor nests usually contain more than 3000 workers and are typically located in rotting fence posts, stumps, old firewood, dead portions of standing trees, and under stones or fallen logs. Nests in a house are typically “satellite” nests to an outdoor nest. Inside, most carpenter ant species establish their first nest in decayed wood frequently softened by dry rot fungus and later expand into sound wood. Nests can also be located in rigid insulation or in walls.
Carpenter ants feed primarily on plant and fruit juices, insects and other arthropods. Inside, they will also feed on sweets, eggs, meats, cakes and grease. The workers forage for distances of up to 300 feet from the nest.
The preferred method for dealing with carpenter ants is prevention. Remove any wood that is touching the ground and replace it with plastic, metal, concrete or pressure treated wood. Also repair any plumbing leaks. All branches of trees and shrubs should be cut back from your home. Caulk any gaps where electrical wire or plumbing fixtures penetrate your home’s exterior.
If, despite your best efforts, you find you do have ants, hire a licensed pest control service.