The black Carpenter Ant gets its common name from the habit of hollowing out galleries in pieces of wood for nesting purposes. This nesting habit can often result in structural damage.
Carpenter Ants are found throughout the United States. Carpenter Ant workers can vary greatly in size, ranging from 1/8” to 1/2”, with black bodies and black or sometimes reddish legs. Reproductive female Carpenter Ants can be as large as 1”, black and usually with wings. The wings of the reproductive female Carpenter Ant are made up of two pairs of wings, one pair noticeably smaller than the other.
The only external indication of a Carpenter Ant infestation, other than the presence of workers and/or swarms, is the appearance of small openings on the surface of the wood. Through these, the Carpenter Ant workers expel debris which consists of sawdust-like shavings and/or fragments of insulation and insect body parts. Carpenter Ants prefer to attack wood softened by fungus and are often associated with moisture problems.
Black Carpenter Ant colonies are of moderate size, usually containing over 3,000 workers (up to 15,000 including satellite nests) when maturity is reached, in about 3 to 6 years. The typical mature colony of western Carpenter Ants contains about 10-20,000 workers, with large colonies having up to 100,000 workers. Developmental time (egg to adult) for workers takes at least 60 days. There is usually one functional, wingless queen per colony. Reproductive Swarmers are not produced until the colony is more than 2 years old. Swarmers can appear from February through June and are often the first and/or only indication of the presence of a Carpenter Ant nest located inside.
Most Carpenter Ant species establish their first nest in decayed wood and later expand or enlarge this nest into sound wood. Inside, nests are located in wood, in insulations and/or in wall voids. Workers are a nuisance when out searching for food but are also destructive to timbers utilized for nesting activities. Outside, nests are typically located in rotting fence posts, stumps, old firewood, dead portions of standing trees, and under stones or fallen logs.
Carpenter Ants feed primarily on insect honeydew, plant and fruit juices, and other insects. Inside, they often feed on sweets, meats, grains, grease and even pet food. The Carpenter Ant workers forage for distances of up to 300 feet from the nest. Carpenter Ants typically enter buildings around door and window frames, eaves, plumbing and utility lines, and shrub tree branches that are in contact with the building. Although some workers are active during the day, most activity is from dusk till dawn, with peak activity between 10 pm and 2 am.
The first step is to determine whether the Carpenter Ants are merely foraging from an outside nest or if there is a nest inside. Once the approximate location of the Carpenter Ant colony has been found, the next step is the targeted treatment in the suspected areas by a trained and licensed pest control operator, which commonly includes drilling and injecting into exterior wall voids, in addition to a perimeter barrier around the foundation of the building.