Most recently reviewed by: Janet Hurley & Pat Porter (2018)
Common Name(s): Carpenter Ants
Pest LocationUrban Structural
Fourteen species of carpenter ants occur in Texas. The largest species is the black carpenter ant, Camponotus pennsylvanicus (Fabricius) and is found primarily in wooded areas outdoors. Common indoor species, Camponotus rasilis Wheeler and C. sayi Emery, have workers that are dull red bodied with black abdomens. Worker ants range in size from 1/4 to 1/2-inch. They can be distinguished from most other large ant species because the top of the thorax is evenly convex and bears no spines. Also the attachment between the thorax and abdomen (pedicel) has but a single flattened segment.
Winged reproductive carpenter ants should not be confused with winged termites (Isoptera). Ants have elbowed antennae, distinctly veined wings of different sizes (large forewings and small hind wings) and a narrow portion of the body (waist) between the thorax and abdomen. The acrobat ants, Crematogaster sp., also occasionally nest in wood. These ants are much smaller and have a heart-shaped abdomen that is often held up over their bodies. They feed primarily on honeydew produced by aphids (Homoptera).
Mouthparts are for chewing.
Origin and Distribution
These ants usually nest in dead wood, either outdoors in old stumps and dead parts of trees and around homes (in fences, fire wood, etc.) or indoors (between wood shingles, in siding, beams, joists, fascia boards, etc.). Ant colonies are often located in cracks and crevices between structural timbers, but the ants can also tunnel into structural wood to form nesting galleries. They often appear to prefer moist, decaying wood, wood with dry rot or old termite galleries. However, damage is often limited because these ants tunnel into wood only to form nests and do not eat wood. Galleries (nesting tunnels) produced by carpenter ants usually follow the grain of the wood and around the annual rings. Tunnel walls are clean and smooth. Nests can be located by searching for piles of sawdust-like wood scrapings (frass) underneath exit holes. These piles accumulate as the nests are excavated and usually also contain parts of dead colony members. Occasionally carpenter ants, particularly Camponotus rasilis Wheeler, nest under stones or in other non-wood cracks and crevices. Foraging worker ants leave the nest and seek sources of sweets and other foods such as decaying fruit, insects and sweet exudates from aphids or other sucking insects.
Habitat & Hosts
Water-damaged or other softened wood is especially conducive to nesting, with gallery expansion into adjacent sound wood as the colony grows. Nests may also be constructed in wall voids, insulation, hollow doors, or wood furnishings or fixtures.
Carpenter ant nests are kept clean, with frass, sawdust-like wood shavings, dead ants, and other debris pushed out of the gallery through a crack or slit, creating telltale dump piles that look like sawdust from a distance.
Carpenter ants will eat fruit, insects, meat, and sugars including insect honeydew. Carpenter ants typically forage in late afternoon and night, up to 200 yards from the nest, and carry food back to the colony.
Ants develop through several stages: eggs, larva, pupa and adult. Larvae are legless and grub-like and pupae are a cream-colored to tan cocoon which are often mistakenly called “ant eggs”. Development from egg to worker ant occurs in about 2 months. Carpenter ants are social insects and live in colonies made of different forms of ants or “castes.” Mature colonies contain winged male and female forms (reproductives), sterile female workers of various sizes, and a wingless 9/16 inch long queen. Winged forms swarm during May through late July. The presence of 3/4 inch long winged forms in the home is an indication that structural damage may be occurring.
ManagementIf you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.
They nest primarily in wood including live trees with heart rot. They can nest in buildings especially in areas of moist wood. In some areas of the U. S. carpenter ants may damage sound, structural wood to excavate nests. More commonly, carpenter ants nest in existing cavities, or in soft or rotting wood of higher moisture content. Smaller species may live in pre-existing voids, such as curtain rods, hollow-core doors, or between studs in walls and around windows. They are scavengers that eat sweets and some insects. Carpenter ants use trees and other plant material as bridges to enter structures. Look for wood shavings and sawdust discarded from the nest. Follow the trail back to the nest. This procedure is especially effective at night during summer months.
Non chemical Control Measures
A primary defense against carpenter ants is to avoid moisture-damaged wood. Regularly inspect and promptly correct roof, window or vent leaks; clogged, damaged or improperly aligned gutters; or wood that may be in contact with soil or vegetation. Prune trees and shrubs in contact with the structure. Move firewood piles or other debris away from the structure. Similarly, decaying or softened wood building elements, such as soft decking and window or door sills, should be repaired or replaced.
Carpenter ants around the home – AgriLife Extension fact sheet by Dr. Mike Merchant
IPM Action Plan for Carpenter Ants this document is peer reviewed recommendations for a management plan for carpenter ants.