Most Wanted Ants: Carpenter ant


October 27, 2020

Photo courtesy of, and copyrighted by, Gene White,

Two black carpenter ants (Camponotus pennsylvanicus) engage in trophallaxis. Photo courtesy of, and copyrighted by, Gene White,

Camponotus spp.

Alias: Carpenter ant


  • The nest galleries some carpenter ant species cut into wood generally are smooth and clean, which is how they earned the “carpenter” moniker.
  • Workers of invasive carpenter species vary in size, among the smallest being those of C. nearcticus, which are 3/16 to 1/4 of an inch long.
  • Carpenter ants seen indoors are mostly black; however, some species, such as C. vicinus, C. chromaiodes, and C. floridanus have reddish body sections and/or leg segments.
  • Polymorphic workers for the larger species vary in size, from 1/4- to 3/4-inch long.

Life Cycle

  • The queen is present in the primary nest, which is located away from the home or infested structure.
  • No egg-laying queen is present in the secondary, or satellite nests, which are located within the structure.
  • More than one satellite nest may be associated with different primary nests, and therefore, separate colonies.
  • Each colony typically has only one egg-laying queen.
  • For most colonies, alates, or winged reproductives, form in three to six years, at which time about 2,500 or more individuals will be present.
  • Populations within colonies vary; some include more than 100,000 individuals.
  • Alates may be produced any time of the year, but usually develop in late summer.


  • Although some carpenter ant species (Camponotus modoc and C. pennsylvanicus) excavate cavities in structural wood and foamboard (EPS) insulation, most structure-invading species are opportunistic nesters, occupying existing cavities/gaps in exterior walls, roofing, and interior features.
  • They often excavate tunnels and galleries in structural wood that already is in a state of decay due to retained moisture.
  • They do not use wood for food.
  • They establish nests in many different outdoor situations, such as tree trunks and branches, stumps, logs, landscaping timbers, fenceposts and sometimes in covered soil.
  • Indoor nests may be found in windowsills, hollow doors, roofs, porch substructures, baseboards, fireplaces, shingles or other naturally hollow areas. A hollow pipe may even serve as a nest.
  • Nesting activities may weaken building structures, but not as seriously as termites.
  • In wooded areas, many colonies may be present around an infested home.
  • Carpenter ants often move into a building solely to scavenge and feed.
  • They may be carried into homes in firewood, or enter and establish colonies via other routes.
  • Foragers can enter homes via tree limbs or wires that touch the house; thus the nest may or may not be inside the home.


  • Foraging ants will travel 100 yards or more from the nest for food.
  • During warm months, they will forage most actively in early nighttime hours.
  • Carpenter ants feed on a variety of animal and plant foods, and will feed on other living or dead insects.
  • They will feed on nearly anything people eat, including sweets. Aphid honeydew is especially appealing.

Range ➔ Various species are widespread throughout the United States.

Prevention ➔ Eliminate moisture and water sources; remove food sources by keeping food sealed; prune shrubs and trees so they do not touch the structure; seal entry points into structures; store firewood and lumber away from the home.

SOURCE: Truman’s Scientific Guide to Pest Management Operations

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