How To Get Rid Of Carpenter Ants In 6 Easy Steps

In the forest, carpenter ants have a job to do, recycling woody debris, such as dead trees and fallen logs. But these large ants become nuisances when they forage or nest inside our homes. “Carpenter ants don’t eat wood, like termites do,” says Eric Benson, PhD, professor emeritus and extension entomologist with Clemson University. “They excavate it to make a nest for their babies.”

Like bees, wasps, and other ants, carpenter ants are social and live in a colony with a single queen and thousands of workers. The queen is found in a tree or log, where she lays her eggs, but the workers carry some of the brood to new locations, or satellite nests, a few hundred feet away, says Benson. Having multiple nest sites helps protect the colony.

These ants are omnivores and eat insects, honeydew from aphids, fruits, and plant juices, but they’ll also forage indoors for water and sugary foods. “If you discover carpenter ants in your home, it’s probably an indication you have a moisture problem. They look for soft, water-damaged wood, then use your house as a satellite nest and incubator for their brood,” says Benson.

Fortunately, the carpenter ant species common in the South typically don’t cause as much damage—and rarely structural issues—as the species found in the Pacific Northwest and Northeast. “Typically, this ant is less concerning in the South than wood-destroying organisms, such as termites,” says Faith Oi, entomologist and extension professor at the University of Florida. “However, you will need to eliminate the colony. If you’re only treating the satellite nest or nests, you’re not getting rid of the problem.” 

Identifying Carpenter Ants

There are many species of carpenter ants, but those most common in the South are black carpenter ants (Camponotus pennsylvanicus), which are a dull black color, and Florida carpenter ants (Camponotus floridanus), which have a black head and a red body, says Oi.

Besides trees, logs, and landscaping timbers, you may find carpenter ants in places such as:

• Areas of poor ventilation, such as in crawl spaces or under porches
• Hollow wooden doors or porch columns
• Leaky window sills and door frames
• Water-damaged wood near attic vents, soffits, and rooflines
• Untreated wood in direct contact with soil, such as porch supports
• Wet insulation
• Florida carpenter ants also may nest under loose debris on the ground, such as boxes and paper bags

Carpenter Ants vs. Termites

Carpenter ants are sometimes mistaken for termites, but they have distinctive differences: Adult carpenter ants have six legs, a narrow waist, and “elbowed” antennae with a bend. The workers range in size from ¼-inch long to 5/8-inch long. In late winter to early spring, carpenter ants swarm to mate and start new colonies. These reproductives will have two sets of wings with the front pair longer than the hind pair.

Termites have a thicker body and antennae that are not elbowed. Workers also are white and smaller than carpenter ants, about 1/8 to 3/16 inch long. When termites swarm, they have two sets of wings which are the same size and length.

Signs You Have Carpenter Ants

Look for these signs to tell if you have an infestation of carpenter ants, say Benson and Oi:

• Large ants foraging, especially after sundown or near water sources such as sinks, showers, tubs, and dishwashers
• Conical piles of rough wood shavings, sawdust, and insect parts, indicating a nest under construction
• Fuzzy grayish-white pupae, which are enclosed in cocoons, indicating there’s an established nest
• Large number of swarming winged ants appearing indoors in late winter to early spring
• Excavated galleries in wood, with a smooth, sandpapered appearance, as opposed to wood damaged by termites, which contains a mud-like material

How To Get Rid Of Carpenter Ants

Seeing one or two ants foraging doesn’t necessarily mean you have an infestation. But if you discover a whole trail, it’s time to investigate further, says Benson.

• Get a positive ID to ensure you have carpenter ants, not termites, because these pests are controlled differently. Contact your local university coop extension service (find yours here) for identification.
• Do some sleuthing to find the main nest. This is difficult, but not impossible. After dark when they’re most active, follow the ants with a flashlight, says Oi. You usually can find their trails if you’re patient. If you find the outdoor nest, you can use a pesticide labeled for carpenter ants, per label instructions.
• Set out baits labeled for carpenter ants. Baits can be effective because ants share food with each other, says Benson. Place them outside your home where you see ants foraging or entering the home. Keep baits out of reach of kids and pets.
• Be patient.  Depending on the time of year, carpenter ants have different food preferences, preferring protein-based baits when raising babies or sugar-based baits at other times, says Oi. If your first bait isn’t working, try a different type.
• Avoid spraying indiscriminately indoors. That’s not going to eliminate the nest, and ants may return when the chemical residue has diminished.
• If you have no success, consult a professional pest control company, which has access to additional products, such as insecticidal dust for use inside wall voids. They also should be able to identify and eliminate the main nest, says Benson.

How To Prevent Carpenter Ants

There are no guarantees, but these tips from Benson and Oi may reduce the likelihood that carpenter ants will move into your home:

• Repair plumbing or roof leaks ASAP, and replace water-damaged wood.
• Seal gaps around doors, window sills, and where utility lines enter the house.
• Make sure basements and crawlspaces are ventilated properly to reduce moisture buildup.
• Stack firewood away from the house, not up against it.
• Avoid hanging wooden flower boxes on the house.
• Clean gutters regularly so water flows away from your house and doesn’t back up into the soffits and under the roofline. “Remember that ants live in a 3D-world. They can enter from the attic and roof, not just from ground level,” says Benson.
• Keep mulch layers up against the house thin, and trim back tree limbs and shrubs so they don’t touch your house and create easy access for foraging ants, says Oi.
• Remove dead trees or rotting stumps, which provide harborage, near your house.
• Forget about “repellants,” such as essential oils or garlic because there’s no research evidence these things work, says Benson.
• If you’ve had problems with carpenter ants in the past, be vigilant. While activity may taper off in the winter, they’re not gone. “Be proactive and act if you see ants in your home in the spring. Don’t wait until their numbers have increased by the height of summer,” says Benson.