Carpenter ants are the largest species of pest ants found in Georgia. They get the name from their habit of chewing wood to create nesting sites. Carpenter ants do not eat wood, they simply excavate cavities in trees and wood products for nesting galleries. These ants can be a nuisance in and around the home because of their large size and sheer numbers.
There are two types of carpenter ants: black carpenter ants and Florida carpenter ants. Black carpenter ants have a dull black coloring and are covered by yellow hairs. Florida carpenter ants have a red head and black abdomen. There are ants of several different sizes in carpenter ant nests, ranging from .25 to .5 inches.
Carpenter ants are active from March until October. They survive the colder months by hibernating in their nests. Nests are most commonly found in areas with high populations of hardwood trees.
These ants are most active at night, starting just after sundown. They emerge about 15 minutes after sunset and leave the nest to forage for food. Unlike other ant species, carpenter ants create semi-permanent trails which they use often for gathering food. They feed mainly in the tree tops, consuming "honeydew" produced by aphids and scale insects. This honeydew is rich in sugar and can sustain entire carpenter ant colonies.
Carpenter ants can make nests both outside and inside of houses. Inside the home, nests are often found in areas containing moisture-damaged wood. This partially rotted material is much easier to chew through than dry wood. The damp wood and warm temperatures inside a home is also conducive to carpenter ant colony survival.
Most outdoor carpenter ant nests are located in tree holes and wounds in the tree trunk. Most mature hardwood trees have holes which make safe, protected nest sites for the ants.
Black carpenter ants are found almost exclusively in tree holes, whereas Florida carpenter ants are more opportunistic and may be found nesting in ground debris.
Finding the nests is the key to controlling carpenter ants. Look for small piles of wood debris resembling sawdust. Carpenter ants found in the home can often be traced back to nests outdoors in nearby trees. Scout for ant movement 15 to 20 minutes after sunset. Use a flashlight to search for the carpenter ants moving along their pathways. A directional pattern will often lead right to the nest.
To treat carpenter nests indoors, either physically remove the nests or treat them with insecticides labeled for indoor ant control. Insecticidal dusts can be used in places where nests are suspected or where ants are foraging. Always wear a protective mask when applying dusts. Aerosol formulations are also handy in helping to eliminate carpenter ant colonies indoors. Avoid water-based and wet insecticide formulation on indoor colonies, as they can damage surrounding materials.
When treating outdoor nests, use liquid insecticide formulations. Apply the product directly to the nest in a tree hole, making sure to saturate the entire nest and all visible ants inside. Most available insecticides will work well on carpenter ants.
If the nest cannot be found, ant baits can be used next to carpenter ant trails.
To protect a house from ant entry, use a liquid insecticide and apply 2 to 3 feet up on outside walls, as well as up to 5 feet away from the house.
Clark MacAllister is the Dawson County extension agent. For more information, call (706)265-2442.