Carpenter Ants in the House
Carpenter ants in the house mean one of two things. Either a colony nests inside, usually in wood that a leak has softened, or workers walk in at night from a nest outdoors, often in a tree. Winged ants swarming indoors and small piles of wood shavings point to a nest inside the house.
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Why Carpenter Ants Show Up Indoors
Carpenter ants are among the biggest ants you will see indoors. Workers measure about 1/4 to 5/8 inch, and winged ants reach 3/4 inch, according to Texas A&M AgriLife's carpenter ant guide. They don't eat wood. They hollow it out for living space and feed on insects, sweets and honeydew, the sugary waste of aphids and scale insects.
Most colonies start outdoors. Texas A&M notes that an indoor infestation usually begins when part of an existing colony moves into the house, and the ants can keep linked satellite nests. Workers travel up to 100 yards from the nest for food, mostly after dark, so the ants on your counter may live in the yard.
Color helps too. In Texas, the species that most often move indoors have a dull red body and a black abdomen. The largest Texas species, the all-black carpenter ant, lives mainly in wooded areas outdoors.
Signs of Carpenter Ants in the House
Some signs point to a nest inside the walls, and others only mean workers are visiting from outside. The table below shows what each sign usually means and where to look next.
| What you see | What it usually means | Where to look |
|---|---|---|
| A few large ants at night, walking a steady line | Foragers, often from a nest outdoors | Trace the trail outside with a flashlight, starting at nearby trees |
| Winged ants swarming inside | A mature colony nesting indoors | Walls and window frames near the swarm |
| Winged ants around porch lights outside | Usually an outdoor colony, no concern by itself | Check whether winged ants also turn up inside |
| Small cones of shredded wood with dead insects mixed in | An active nest gallery just above | A tiny hole in the trim, window frame or door frame |
| Workers gathering near a tub, sink or leaky window | A satellite nest in wood a leak has soaked | Sink cabinets, tub walls, window sills |
| Faint rustling inside a wall at night | A possible nest in a wall void | Walls near roof leaks, clogged gutters or plumbing |
A frass pile is the most useful find, because the nest opening sits right above it. It doesn't always appear, though, since the ants sometimes dump debris into hollow wall voids.
What Carpenter Ant Damage Looks Like
Carpenter ant damage looks clean. The ants chew tunnels, called galleries, along the grain of the wood and favor the softer, lighter growth rings. Gallery walls come out smooth, almost sanded. The ants haul the debris out through a small kick-hole, where it builds into a cone of shredded wood and dead insects.
Termite damage looks dirty by comparison. Termites line their galleries with mud, and the subterranean termites we deal with in DFW also build mud tubes and leave no shavings or pellets. Fresh wood bits under a window frame mean carpenter ants, while mud means termites. Wings differ too, since an ant's wings are about as long as its body or shorter, and a termite's wings run longer than the body, up to twice its length.
AgriLife calls Texas carpenter ants nuisance pests that rarely damage framing lumber. Most nest in wood that is already rotten or termite-damaged, so the bigger worry is often the leak or rot they point to.
They still matter when you sell. Carpenter ants count as wood-destroying insects, so a buyer's wood-destroying insect inspection covers them.
Where Carpenter Ants Nest Around DFW Homes
Carpenter ants need wood that water has softened. Indoors, AgriLife lists leaking door and window frames, wood around kitchen and bathroom plumbing, and voids around tubs and showers. Clogged gutters and roof leaks soak wood that ants move into too. They even nest in attic and wall insulation, including rigid foam board.
Outdoors, the nest is often in a tree, and in DFW the crape myrtle is the tree to check first. When a customer has carpenter ants, our technicians very often find a crape myrtle just outside the house with ants trailing on it. Food may be part of the draw. Texas A&M reports that crape myrtle bark scale turned up in Richardson in 2004 and has spread to many DFW crape myrtles. The scale leaves heavy honeydew and black sooty mold on the bark.
From the tree, workers follow branches, fence rails and utility lines to the house, then slip in through cracks, attic vents and spots where limbs touch the roof.
What to Do About Carpenter Ants Indoors
First find out whether the nest is inside or outside, then take away what drew the ants in.
- Watch on a warm night with a flashlight and see whether the trail leads outdoors or into a wall.
- Fix leaks around tubs, sinks, windows, gutters and the roof, and replace rotted wood.
- Trim crape myrtle and other limbs so they don't touch the roof or walls.
- Move firewood, stumps and old landscape timbers away from the house.
- Skip spraying the trail, which kills a few workers and leaves the nest alone.
Texas A&M also advises against the containerized ant baits sold in grocery and hardware stores, since those target ants in general.
A nest inside the house needs treatment at the source. With carpenter ant control, a technician confirms the species, finds the nest and treats it directly. When the nest sits out of reach, non-repellent sprays and baits let workers carry the treatment back to the colony. Homes near our Southlake office can read how we handle carpenter ants in Southlake. Anywhere in DFW, get a price online or by phone.
Carpenter Ants in the House FAQ
Should I be worried if I find a carpenter ant in my house?
Not right away. A single large ant at night is usually a forager, and Texas species rarely cause serious structural damage. Frass, winged ants indoors or ants near a leak call for action.
What month are carpenter ants most active?
Winged carpenter ants swarm from May through late July in Texas, based on Texas A&M's insect field guide. Workers forage most on warm nights.
Do carpenter ants ever go away?
Not while the nest sits in wet wood. AgriLife says colonies stay small for 2 or 3 years, then grow fast and can hold 3,000 or more ants by year 4 to 6. Drying out the wood takes away the reason they stay.
Should I squish carpenter ants?
Squashing a few workers does no harm, but it does nothing to the nest. Carpenter ants can bite, though they don't sting. Save one in a sealed bag or snap a sharp photo so a technician can confirm the species.
