How to Get Rid of Carpenter Ants (2026 Guide)

Last updated: March 4, 2026

By James — 25-year pest control industry veteran

Knowing how to get rid of carpenter ants is critical for protecting your home from structural damage. Unlike most household ants that are simply a nuisance, carpenter ants excavate galleries inside wood to build their nests. They do not eat wood the way termites do, but the tunneling weakens framing, joists, and other structural components over time. A mature carpenter ant colony can contain 10,000 to 50,000 workers, and left untreated, the damage grows worse every year.

This guide covers how to identify carpenter ants, recognize the signs of an infestation, locate their nests, apply effective DIY treatments, and know when professional help is the better option. For detailed pricing on professional treatment, see our carpenter ant treatment cost guide.

Carpenter Ants vs. Regular Ants

Carpenter ants are among the largest ants in North America, measuring 1/4 to 1/2 inch long. Most are black, though some species are dark brown, reddish, or a combination of black and red. They have a single node (petiole) between the thorax and abdomen, a smooth rounded back profile, and elbowed antennae. Worker ants vary in size within the same colony, which is a helpful identifying trait.

Regular household ants, such as odorous house ants and pavement ants, are much smaller (1/16 to 1/8 inch) and forage in large, visible trails along countertops and floors. Carpenter ants tend to forage individually or in smaller trails, often at night. They are also more likely to be found near wood structures rather than in kitchens or pantries, though they will enter kitchens to feed on sugary foods and protein.

The key behavioral difference is nesting. Regular ants nest in soil, under pavement, or in wall voids without damaging the structure. Carpenter ants actively excavate wood to create smooth, clean galleries for their colony. This wood-destroying behavior is what makes them a serious concern for homeowners. For a broader overview of ant control, see our guide on how to get rid of ants.

Carpenter Ants vs. Termites

Carpenter ants and termites are frequently confused because both are associated with wood damage. However, their biology and the damage they cause are quite different. Correctly identifying which pest you have determines the right treatment approach.

If you find mud tubes on your foundation or walls, you are likely dealing with termites rather than carpenter ants. See our termite treatment cost guide for information on termite control options and pricing.

Signs of a Carpenter Ant Infestation

Carpenter ant infestations can go unnoticed for months or even years because the colony is hidden inside wall voids and structural wood. Knowing the early warning signs helps homeowners catch the problem before significant damage occurs.

Frass (sawdust piles)

Frass is the most reliable sign of carpenter ant activity. As ants excavate galleries, they push wood shavings, dead ant body parts, and other debris out of small openings called kick-out holes. The resulting piles look like fine sawdust or pencil shavings and typically accumulate below baseboards, window frames, door frames, or along the top of foundation walls. Frass piles that reappear after being cleaned up confirm active nesting.

Rustling sounds in walls

A large carpenter ant colony produces a faint rustling or crinkling sound inside walls, especially at night when the ants are most active. Tapping on a wall near a suspected nest may trigger louder rustling as the ants respond to the disturbance. If you hear these sounds consistently in the same area, it is a strong indicator of a nest inside the wall cavity.

Winged swarmers in spring

Carpenter ant colonies produce winged reproductive ants (swarmers) once the colony is mature, usually after three to five years. Swarmers emerge in spring, typically between March and June, and are often found near windows and light sources inside the home. Finding winged carpenter ants indoors during spring is a strong indicator of an established colony within the structure. Finding them outdoors near the house is less conclusive but still worth investigating.

Scattered large ants, especially at night

Seeing occasional large black ants in your home, particularly in kitchens, bathrooms, or near exterior walls, suggests carpenter ants are foraging from a nearby nest. Carpenter ants are most active at night, so spotting them after dark along baseboards, countertops, or around pet food dishes is a common early sign. Even a few ants per week may indicate a colony nearby.

Finding the Nest

Eliminating a carpenter ant colony requires locating the nest, which can be the most challenging part of treatment. Carpenter ants typically maintain a parent colony outdoors and one or more satellite colonies inside the home. The parent colony is usually in a tree stump, dead tree, or landscape timber, while satellite colonies occupy moist wood inside walls, attics, or crawl spaces.

Follow the ant trails at night

The most effective way to find a carpenter ant nest is to follow their foraging trails after dark. Between 10 p.m. and 2 a.m., use a red-filtered flashlight (which does not disturb them) to trace their movement from food sources back toward the nest. Worker ants follow the same paths repeatedly, and the trail typically leads to a wall void, door frame, or window frame where they enter the nesting area.

Check moisture-prone areas

Carpenter ants strongly prefer wood that has been softened by moisture. Focus your inspection on areas around leaky pipes, dishwashers, and washing machines. Check the wood framing near bathrooms, under kitchen sinks, around window condensation, and in basements or crawl spaces where humidity is high. Roof leaks and poor attic ventilation also create conditions that attract carpenter ants.

Tap-test suspect wood

Tap along baseboards, window frames, and wall studs with the handle of a screwdriver. Sound wood produces a solid tone, while wood that has been hollowed out by carpenter ant galleries sounds noticeably hollow. If tapping triggers a burst of rustling activity behind the wall, you have likely found the nest location.

Look for frass exit holes

Small, round or oval openings (about 1/8 inch) in wood surfaces or drywall are kick-out holes where carpenter ants expel frass. These holes are often found along the bottom edge of baseboards, on exposed beams, or on the underside of window sills. A pile of frass directly below one of these holes pinpoints a nesting gallery behind the surface.

DIY Treatment Methods

DIY treatment can be effective for small, accessible carpenter ant infestations, particularly when you can locate the nest. The key is targeting the colony directly rather than just killing foraging workers.

Bait stations

Carpenter ant bait stations use a slow-acting insecticide mixed with a food attractant. Foraging ants consume the bait and carry it back to the colony, where they share it with other workers, larvae, and the queen through trophallaxis (food sharing). This method can eliminate entire colonies over two to four weeks. Place bait stations along active ant trails, near entry points, and close to areas where you have seen carpenter ant activity.

For best results, use bait products specifically formulated for carpenter ants, as they prefer protein-based baits during certain seasons and sugar-based baits during others. Avoid using repellent sprays near bait stations, as they will deter ants from approaching the bait. Patience is important because the poison must spread through the entire colony before activity stops.

Boric acid

Boric acid is a widely used treatment for carpenter ants. It can be applied as a dust directly into wall voids, kick-out holes, and gallery openings using a hand duster or squeeze bottle. When ants walk through the dust, it clings to their bodies and is ingested during grooming, eventually killing them. Boric acid dust can also be transferred to nestmates through physical contact.

To apply, drill small (1/8 inch) holes into the wall at suspected nest sites and puff a light coating of boric acid dust into the void. The dust should be barely visible; heavy application causes ants to avoid treated areas. Boric acid is relatively low in toxicity to humans and pets but should still be applied in areas that are not readily accessible to children.

Eliminating moisture sources

Because carpenter ants depend on moist wood for nesting, fixing moisture problems is both a treatment and prevention step. Repair leaky faucets, pipes, and roof flashing. Improve ventilation in crawl spaces, attics, and bathrooms. Replace wood that has been water-damaged or is showing signs of rot. Addressing the underlying moisture issue makes the nesting site inhospitable and can force satellite colonies to relocate or weaken.

Removing wood-to-soil contact

Wood that directly contacts soil absorbs ground moisture and provides a convenient bridge for carpenter ants to move between outdoor and indoor nests. Check for and eliminate direct wood-to-soil contact around your foundation, including porch posts, deck supports, siding, and door frames that rest on or near the ground. Maintain at least six inches of clearance between soil and any wood structural elements.

Perimeter treatment

Applying a non-repellent insecticide around the exterior perimeter of your home creates a barrier that carpenter ants unknowingly walk through. Non-repellent products are preferred because ants do not detect them and therefore do not avoid treated areas. They pick up the product on their bodies, carry it back to the nest, and transfer it to other colony members through contact. Follow label directions carefully for any insecticide product.

When to Call a Professional

While DIY methods work for small, accessible infestations, certain situations call for professional treatment. The cost of professional carpenter ant treatment typically ranges from $300 to $600, which is far less than the cost of repairing structural damage from an untreated infestation. See our carpenter ant treatment cost guide for a full pricing breakdown.

Multiple satellite colonies

Carpenter ant colonies commonly establish two or more satellite nests inside a home in addition to the parent colony outdoors. If you are finding frass in multiple locations, seeing ants in several rooms, or treating one area only to have ants appear elsewhere, the colony has likely spread to multiple nesting sites. Professionals have the tools and experience to locate and treat all nest sites in a single service visit.

Nest inside wall voids

When the nest is located deep inside a wall cavity, behind siding, or within structural framing, it is difficult to treat effectively with over-the-counter products. Pest control professionals use specialized equipment such as wall void injectors and borescopes (small cameras) to locate and treat nests without unnecessary damage to walls. They can also identify the extent of wood damage and advise on needed repairs.

Recurring infestations

If carpenter ants return within weeks or months after DIY treatment, the colony was not fully eliminated. This often happens when satellite nests or the parent colony were not reached by the treatment. A professional inspection can identify the source colony, trace the entry points, and apply commercial-grade products that provide longer-lasting residual protection.

Visible structural damage

If you can see damaged or hollowed-out wood, the infestation has been active for a considerable time. At this stage, the priority is stopping further damage and assessing what repairs are needed. A professional pest control technician can coordinate with a contractor if structural repairs are required, and their treatment will be more thorough than DIY approaches for established infestations.

Professional Treatment Methods

Professional pest control companies use several methods to eliminate carpenter ant colonies, often combining two or more approaches depending on the location and severity of the infestation. For a detailed cost comparison, see our ant exterminator cost guide.

Most professional treatments include a follow-up visit two to four weeks after the initial service to verify that the colony has been eliminated. Many companies also offer annual carpenter ant warranties that cover re-treatment if ants return. Given the risk of structural damage, the warranty is often worth the additional cost.

Prevention

Preventing carpenter ant infestations focuses on eliminating the moisture and access points that attract them to your home in the first place.

• Fix all moisture problems. Repair leaky pipes, faucets, and roof flashing. Ensure proper ventilation in crawl spaces, attics, and bathrooms. Carpenter ants cannot easily colonize dry, sound wood.
• Replace damaged wood. Remove and replace any wood that shows signs of water damage, rot, or fungal decay. Pay special attention to window sills, door frames, fascia boards, and sill plates.
• Eliminate wood-to-soil contact. Maintain at least six inches of clearance between soil and all wood components of the home, including siding, porch supports, and deck framing.
• Store firewood away from the house. Keep firewood at least 20 feet from the foundation and elevate it off the ground. Firewood is one of the most common harborage sites for carpenter ant colonies.
• Trim trees and shrubs. Cut back branches and vegetation that touch the house. Carpenter ants use branches, utility lines, and vines as bridges to access the structure from outdoor nests.
• Remove dead wood from the yard. Old tree stumps, fallen logs, and dead branches in the yard provide ideal nesting sites for parent colonies. Removing these reduces the population near your home.
• Seal entry points. Caulk cracks along the foundation, around windows, and where pipes and utility lines penetrate the walls. Check and repair gaps around dryer vents, outdoor faucets, and cable lines.
• Direct water away from the foundation. Ensure gutters are clean and downspouts discharge at least three feet from the house. Grade soil away from the foundation to prevent pooling.

For a broader look at pest control pricing and service options, visit our pest control cost guide.

Frequently Asked Questions