By Beverly Adams, ANR Program Assistant, UGA Extension Forsyth County

close-up image of a carpenter ant
Large size and yellow hairs on the abdomen are identifying features of carpenter ants. Photo by David Cappaert, UGA Bugwood.org.

Carpenter ants are the largest of the pest ants found in our area. There are two species in Georgia: black carpenter ants and Florida carpenter ants. Black carpenter ants are dull black with yellowish hairs covering their abdomens. Florida carpenter ants have a deep reddish colored head and thorax and a shiny black abdomen. They vary in size from ¼ to ½ inches long.

Carpenter ants are active in Georgia from March through the fall. They’re called carpenter ants because they chew up wood to create nesting galleries. They are most active at night, leaving the nest in large numbers shortly before sundown to search for food. In the evening, the ants use trails as they emerge and return to their nest. They feed in tops of trees where they consume honeydew from aphids and scale insect that feed on the tree’s sap.  

sketch showing what carpenter ant damage looks like in wood.
Carpenter ant life stages and examples of structural damage. Illustration by Art Cushman, USDA Systematics Entomology Laboratory, Bugwood.org.

To eliminate carpenter ants, find the nest and remove it. Nests may be inside or outside the home. Inside, carpenter ants seek moisture damaged wood because damp wood is easier to chew than dry wood. Remove indoor nests or treat them with an insecticidal dust or aerosol labeled for ant control indoors. Apply dusts so that a very thin film settles in treated areas. Always wear a protective mask when applying dusts.

Outdoors, black carpenter ants nest in hardwood trees with hollow trunks or tree holes. Sawdust at the base of trees is a sign that black carpenter ants are present. Florida carpenter ants nest under loose debris. Because carpenter ants use permanent trails, their movement will lead you to the nest.

To treat outdoor nests, pour a water-based, liquid insecticide into carpenter ant nests located in tree holes. This may require pouring one gallon or more of liquid insecticide into the nest.

Perimeter treatments prevent ants from entering structures. Spray exterior walls with a water based, liquid insecticide two to three feet up from soil level, and spray the ground (shrubbery, mulch, flower beds, etc.) five feet out from each wall. Spray as many areas traveled by carpenter ants as possible and concentrate spray treatments to areas where ants might enter the structure. Apply a liquid insecticide to the trunk of each tree on which carpenter ants have been seen. Perimeter treatments should be re-applied every 4 to 6 weeks during the summer and within a week following a heavy rain. Eliminate excess moisture, keep rain gutters clean and trim tree limbs away from homes for control.

If you cannot locate the nest, indoors use liquid baits and baits contained in childproof, plastic bait stations; outdoors use liquid and granular baits. Alternatively, consider contacting a licensed pest control company if nests are difficult to find.

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