If you see a carpenter ant, you’d be forgiven for mistaking it for a termite. They’re both winged, for starters (though carpenter ants eventually lose their wings). And they both cause structural damage in your home by destroying the wood.

But carpenter ants, unlike termites, don’t eat wood. Instead, they move it aside as they burrow into it to create tunnels and nests. The longer a carpenter ant colony is in your home, the greater the potential damage. Structural wood can be weakened when carpenter ant damage is severe, according to the University of Minnesota Extension.

Spring brings the beginning of swarming season, when queen carpenter ants start searching for a home for new nests. After she and her winged helpers land (possibly inside your home), they lose their wings and look like regular (albeit large) ants.

If you notice a small number of ants in your home, it’s likely there’s no indoor nest — yet. But a large swarm, or ants in your home throughout the winter, could be a sign of an indoor nest. Here’s what to do.

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1. Confirm they’re carpenter ants. Carpenter ants are large, often dark-colored and narrow-waisted, unlike termites, which are light-colored with a broad mid-section. But size and color aren’t sure indicators because some regions have more than one species, so it’s worth checking. Your local county extension office may be a good resource. (Extension offices are tied to land-grant universities and their research.)

2. Locate the nest. Carpenter ants have two kinds of nests: parent and satellite.

  • Parent nest. Seventy-five percent of parent colonies are located outdoors in moist wood, such as a tree stump, rotting tree, old boards or decayed wood. It might even be on a neighbor’s property if houses are closely spaced (nests can be up to 100 yards away). Finding it will require sleuthing, and you may not be successful.
  • Satellite nest. These are indoor nests, found in moist wood, such as around bathroom or kitchen fixtures, showers, sinks and dishwashers, as well as hollow spaces like wall voids and door voids. Carpenter ants also like foam and fiberglass insulation, attic spaces and subfloor insulation. Look for moist wood and coarse sawdust from chewing, and listen for rustling sounds, especially at night. Try luring ants out with bait (a little honey or jelly on a square of cardboard works well; in spring, the University of Minnesota Extension recommends using tuna packed in water). Then remove the bait and watch where they go.

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3. Remove the nest. It’s not easy to get rid of a nest on your own, especially if it’s inside a wall or other inaccessible location. But if you can get to it, physically removing it is better than using chemicals, according to the Washington Toxics Coalition, an organization dedicated to protecting public health and the environment. They say an accessible nest and stray ants can be captured with a good shop vacuum. But if you can’t find the nest or it’s inaccessible, or you don’t own a shop vacuum, it’s time to call an expert.

Find a company that uses integrated pest management (IPM) methods rather than one that simply plans to blast chemicals. “The concept behind IPM management is you look at physical controls and biological controls, and then only if those fail do you go to least toxic chemicals,” says Erika Schrader, science director at Washington Toxics Coalition.

To choose a reputable company, she suggests asking about their “IPM approach” (if they promote insecticides, that’s a red flag) and how knowledgeable they are about carpenter ants.

Prevent a return trip

Once your ant colony is taken care of, here’s how to keep ants from returning.

Trim trees and shrubs. Keep foliage, including tree branches, trimmed away from your house so it doesn’t become a bridge. Remove old stumps and other rotten wood sources. If houses are closely spaced, consider talking with neighbors about their wood sources. Carpenter ants can be contagious.

Relocate firewood. If you have firewood stacked up against the house, move it away from the structure and elevate it off the ground.

Take care of moisture. Repair damaged or rotten wood on the house or garage, and make sure no soil is in contact with wood structures (house, deck, porch). Check your gutters, make sure water drains adequately away from the house and make sure your attic is vented properly. Be sure to caulk any access points.

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Joanna Nesbit is a freelance writer specializing in education, parenting, lifestyle and family travel.