There are many species of carpenter ants around the U.S., and all of them make their nests in wood. If left unchecked, carpenter ants can cause significant damage to homes, garages, sheds, and other wood-framed structures. If you see large, winged ants in or around your home, confirm that they are carpenter ants and take steps to eliminate the pests as soon as possible.
Identifying Carpenter Ants
The carpenter ant is one of the largest ant species in the U.S., but seeing a large ant does not necessarily mean you have carpenter ants—and seeing only small ants doesn't mean you don't! This is because the different "castes" (workers, soldiers, queen, etc.) and sexes of carpenter ants can be very different in size. For example:
- Workers are only about 1/4 to 5/8 inch in length and are the most commonly seen.
- Male carpenter ants are about the same size as the workers, but they are generally seen only when they fly from the nest to mate with the queen (that is their only purpose in life!).
- The queen is the largest of the species and may be two or three times larger than the workers.
8 Ways to Differentiate Between Carpenter Ants and Termites
Carpenter ant coloring also can vary, but the most common colors are black or dark brown and can include coloration of reddish-orange or yellow. Worker ants are wingless and are typically 1/4 to 1/2 inch long. Winged ants have two sets of wings, with the front set being longer than the rear set. This variation in wing size helps to distinguish carpenter ants from winged termites, which have two sets of wings that are roughly equal in size.
Carpenter Ant Behavior
Carpenter ants do not eat the wood in which they nest but rather chew it with their very large mandibles to create galleries and connecting tunnels to nest in (termites, by contrast, do eat the wood in which they nest). The ants damage structures through the excavation of their extensive galleries and tunnels.
Carpenter ants tend to nest outdoors in dead and decaying wood, such as hollow and rotting trees, old stumps, and even firewood. They can also nest in homes and buildings, in enclosed areas where the wood is damp, wet, or decayed. If infestations grow, the carpenter ant colony may expand into sound wood. These ants have also been found in foam insulation. They usually have more than one nesting site, including a parent and satellite colonies.
Carpenter ants feed on proteins and sugars, such as meats, sweets (syrup, honey, jelly, etc.), and honeydew produced by aphids. The ants may forage in the home for food, but this will occur primarily at night in the spring and summer. They can't sting, but they can inflict painful bites with their powerful jaws, and they will spray formic acid into the wound, causing a burning sensation.
How to Know if You Have an Infestation
You may have an infestation if you have seen the ants in your home or building during the late fall, winter, or early spring. However, one or two in the spring or summer does not necessarily mean that you a problem. Be aware that what look like flying ants emerging from your home in the spring may, in fact, be termites. Ants found in or near wet or spongy wood, particularly around leaky pipes, drains, walls or roofing, are likely to be carpenter ants.
Carpenter Ant Control
You can control carpenter ants with chemical or bait treatments, but the most effective and lasting form of control is replacing any wet and damaged wood in which the carpenter ants are nesting and to repair the conditions causing the damage, such as roofing or plumbing leaks or other moisture issues.
To help prevent future infestation, eliminate any direct contact between the structure and surrounding soil, plants, or mulch. For example, trim trees and shrubs away from the home or building, keep any wood materials from contacting soil, seal cracks and openings in the foundation, and store firewood well away from the home.
If the infestation seems to be extensive, you are having difficulty finding or exterminating the ants, or you just don't want to do it yourself, contact a pest control professional.
"Carpenter Ants." University of Minnesota Extension.
"Biology and Management of Carpenter Ants." University of Georgia Cooperative Extension.