How to Get Rid of Carpenter Ants for Good
To get rid of carpenter ants, find the nest by following foraging ants to damp or damaged wood, treat it with slow-acting bait or a labeled dust/foam applied into the nest or wall void, and fix the moisture that attracted them. Because the nest is usually hidden, difficult or recurring cases are best handled by a licensed pest-control professional.
By Sarah Bell
·Home Editor ·
·
6 min read
The key to how to get rid of carpenter ants is to locate the nest by following foraging ants to damp or damaged wood, treat the nest with slow-acting bait or a labeled dust or foam, and fix the moisture problem that drew them in. Carpenter ants don’t eat wood the way termites do — they tunnel through it to nest — so the goal is killing the colony and removing the damp conditions it depends on. Because nests are often hidden inside walls, stubborn cases are best left to a licensed pest-control professional.
How do I know if I have carpenter ants?
Carpenter ants are large (often black, sometimes dark red or brown) and usually seen indoors in spring and summer. Watch for these signs:
- Frass: coarse, sawdust-like debris mixed with insect parts and insulation, found below baseboards, under windows, near door frames, or along basement and garage walls.
- Sound: a faint rustling or crunching inside walls or wooden structures, most noticeable in quiet rooms at night.
- Ants indoors: steady trails of big ants, especially at night, often near kitchens or bathrooms.
- Winged ants: swarmers indoors can mean an established nest nearby.
Carpenter ants vs. termites: what’s the difference?
People often confuse the two, but the treatment differs. Carpenter ants have a pinched waist, bent antennae, and (when winged) unequal wing pairs; they push wood debris out as frass. Termites have a straight waist, straight antennae, equal wings, and actually consume wood, leaving mud tubes rather than clean sawdust. If you find mud tubes or suspect termites, that’s a separate problem that needs a termite inspection.
How do I find the carpenter ant nest?
Finding the nest is the key to success, because killing foragers alone won’t stop the colony. Carpenter ants are most active after dark, so:
- Place a small amount of sweet bait (honey or sugar water) where you see ants.
- Watch which direction they carry food and follow the trail toward an entry point.
- Tap along studs, headers, and sills with a screwdriver handle — a hollow sound suggests excavated wood.
- Focus on damp or water-damaged areas: around windows, under roof leaks, behind dishwashers, near tubs, in basements, and around outdoor faucets.
How do I treat carpenter ants?
Slow-acting bait is effective because foraging ants carry it back and share it with the colony, including the queen. Expect to see more ant activity for the first two to three days, and give it roughly three to seven days to work. Place bait along trails rather than spraying the ants, since a repellent spray can scatter the colony and make baiting fail.
If you can access the nest or the wall void, labeled dusts or foams applied directly into the void can treat the colony at its source. Always follow the product label for where and how much to apply, and keep products away from children and pets. Outdoors, trimming branches that touch the house and moving firewood away from walls removes bridges and harborage.
Carpenter ant control at a glance
| Approach | How it works | Time to results | Best for |
|---|---|---|---|
| Slow-acting bait | Carried back to the colony | ~3–7 days | Reaching a hidden nest |
| Dust/foam in void | Direct nest treatment | Fast if nest found | Known nest location |
| Moisture repair | Removes the attraction | Prevents return | Long-term control |
| Professional service | Locates and treats nest | Fast + thorough | Hidden or recurring nests |
How do I prevent carpenter ants from coming back?
Carpenter ants target moisture, so prevention centers on keeping wood dry:
- Fix leaks around roofs, windows, plumbing, and gutters.
- Replace water-damaged or rotting wood promptly.
- Improve ventilation in crawlspaces, attics, and basements.
- Keep firewood, mulch, and vegetation away from the foundation.
- Seal gaps and cracks where ants enter.
Outdoor nests often feed indoor activity, so treat the yard as part of your home. Keep tree branches and shrubs trimmed back from the roofline and siding, since overhanging limbs act as highways into the house. Store firewood off the ground and well away from exterior walls, and clear out old stumps or decaying logs where satellite colonies like to settle.
How much damage can carpenter ants cause?
Carpenter ants work more slowly than termites, and they target wood that is already damp or decaying, so a single small colony rarely causes dramatic harm overnight. The concern is time: a mature or satellite colony left untreated for months or years can hollow out structural timbers, window frames, and sills, leading to costly repairs. Because the damage happens out of sight inside walls, many homeowners don’t notice until they spot frass or hear activity. Treating promptly and fixing the moisture that attracted the ants keeps a minor nuisance from becoming a structural problem.
When should I call a pest-control professional?
Call a licensed pest-control professional if you can’t locate the nest, the nest is inside a wall or ceiling, you see winged ants emerging indoors, or activity continues after DIY baiting. Winged ants indoors in particular suggest an established colony mature enough to produce reproductives. Pros can trace hidden galleries, treat voids safely, and confirm the colony is gone — important because an untreated nest can keep weakening structural wood. Treatment costs vary with the severity and nest location, so it’s worth getting a couple of estimates and asking whether a follow-up inspection is included.
Frequently asked questions
Do carpenter ants actually eat wood?
No. Unlike termites, carpenter ants don’t eat wood — they excavate galleries in damp or decaying wood to build their nest and push the debris out, leaving sawdust-like frass.
What does carpenter ant frass look like?
Frass looks like coarse sawdust, often mixed with insect parts and bits of insulation. You’ll typically find it below baseboards, under windows, near door frames, or along basement and garage walls.
How do I find the carpenter ant nest?
They’re most active after dark. Put out a dab of sweet bait like honey or sugar water, watch which way the ants carry it, and follow the trail. Tapping studs and sills for a hollow sound also helps locate excavated wood.
How long does carpenter ant bait take to work?
Slow-acting bait usually takes about three to seven days to show results, and you may see more ant activity in the first two to three days as foragers carry it back to the colony. That increase is normal.
Are carpenter ants as damaging as termites?
They can weaken wood over time, but they generally work slower than termites and prefer wood already softened by moisture. Still, an untreated nest can cause real structural damage, so don’t ignore it.
When should I call a professional for carpenter ants?
Call a licensed pest-control professional if you can’t locate the nest, the nest is inside a wall or ceiling, you see winged ants indoors, or activity continues after DIY baiting.