Finding big black ants crawling around your house can be pretty scary, especially when you realize they might be carpenter ants. These wood-destroying pests can cause serious damage to your home if you don’t take action quickly. Unlike regular ants that just want your food, carpenter ants actually tunnel through wood to build their nests.
The good news is that learning how to get rid of carpenter ants doesn’t have to be impossible. With the right approach and some patience, you can eliminate these pests and protect your home from expensive repairs down the road.
Carpenter ants don’t actually eat wood like termites do. Instead, they chew through it to create smooth tunnels where they live. This can weaken wooden structures over time, including floor joists, wall studs, and support beams. The damage happens slowly, sometimes taking years to become noticeable, which is why quick action is so important.
This guide covers proven methods that really work, from simple DIY solutions to professional treatments. Whether you’re dealing with a small problem or a major infestation, you’ll find the right approach here.
1. Find and Locate the Carpenter Ant Nest
Before you can get rid of carpenter ants, you need to find where they’re living. Look for piles of fine sawdust called frass near wooden structures. This clean sawdust is different from termite damage because it doesn’t contain mud or soil. You might also hear faint rustling sounds coming from inside your walls, especially at night when carpenter ants are most active.
Seeing large black ants during the day, particularly in late winter or early spring, usually means there’s a nest somewhere inside your house. If you spot winged ants indoors, that’s a strong sign of a mature colony that’s been around for at least two years.
Put small amounts of honey mixed with water in bottle caps and place them along your foundation at night. Follow the ant trails back to their source, which could be anywhere from right inside your house to 300 feet away outdoors. Check moisture-damaged areas around chimneys, skylights, plumbing, crawl spaces, and wall voids near windows and doors.
2. Use Targeted Ant Baits
Baiting is one of the most effective ways to get rid of carpenter ants because it targets the entire colony. Mix poisonous gel bait from hardware stores with one teaspoon of sugar and one teaspoon of milk. This combination attracts carpenter ants while ensuring they carry the poison back to their nest. The key is using slow-acting poison that won’t kill ants before they reach the colony.
Place bait stations near your home’s foundation, firewood piles, tree stumps, and any visible ant trails. Use liquid baits in childproof plastic stations indoors, and both liquid and granular baits outdoors. Put granular baits in quarter-sized piles where ants travel.
Baits can take several weeks or even months to completely control carpenter ant colonies, so be patient. Never spray insecticides near bait stations, as this prevents ants from feeding and ruins the baiting process. If ants ignore your bait after 24 hours, try a different type or move it to a new location.
3. Apply Insecticidal Dust Directly to Nests
When you can reach the carpenter ant nest, applying insecticidal dust gives you the fastest results. D-Fense Insecticide Dust works well but contains chemicals harmful to children and pets, so proper application is crucial. Always wear a respirator and gloves when handling any insecticidal dust.
Use a bulb duster to blow dust directly into wall voids where carpenter ants are nesting. Apply only a very thin layer, as too much dust will repel ants and cause them to move elsewhere. Access wall voids through electrical switch plates, small drilled holes, or existing openings.
Wipe up any visible excess dust with a damp paper towel after application. Insecticidal dust works better than sprays because it travels through the network of tunnels carpenter ants create and lasts longer than liquid treatments.
4. Try Boric Acid Treatment
Boric acid provides a powerful yet relatively low-toxicity option for carpenter ant control. Mix powdered sugar and boric acid in a ratio of 1/3 sugar to 2/3 boric acid. The sugar attracts ants while the boric acid poisons their stomachs and nervous systems.
Pour your mixture into bottle caps and place them where you’ve seen carpenter ant activity. Wear gloves when handling boric acid, as it can cause skin irritation. Keep the mixture away from children and pets, as it can cause digestive problems if eaten.
You can also apply boric acid as a dust using a bulb duster to blow it into wall voids and nesting areas. When worker ants consume the mixture, it kills them and often gets carried back to the nest where it affects other colony members.
5. Apply Diatomaceous Earth for Natural Control
Food-grade diatomaceous earth provides an effective, eco-friendly solution that damages ants’ exoskeletons and causes dehydration. Always use food-grade DE, never pool-grade or chemically treated versions. You can buy it at hardware stores, garden centers, and online retailers.
Spread a thin layer of DE along ant trails, around entry points, and where you’ve seen ant activity. Use a duster, salt shaker, or paintbrush to apply it precisely in baseboards, window sills, and areas under sinks. Focus on cracks and crevices where ants travel.
DE only works when dry, so reapply after wet weather or cleaning. Most ants die within 12 to 24 hours of exposure, but eliminating an entire colony can take several days to a week. While effective against worker ants, DE may not reach hidden nests or eliminate queens in severe infestations.
6. Use Non-Repellent Insecticide Sprays
Non-repellent insecticides allow ants to walk through treated areas and spread poison to other colony members before dying. Termidor SC provides long-lasting outdoor protection for up to seven years. For indoor treatment, Phantom works well because it’s odorless and safe for cracks and crevices.
Always use baits first, then apply sprays around your home’s exterior and entry points. This timing maximizes the chance that ants will consume bait before encountering treated surfaces. Spray exterior walls 2 to 3 feet up from the ground and extend treatment 5 feet out from the foundation.
Apply liquid insecticide to tree trunks where you’ve seen carpenter ant activity. Reapply perimeter treatments every four to six weeks during summer and within a week after heavy rain to maintain effectiveness.
7. Create Natural Repellent Sprays
Natural repellent sprays provide safer alternatives to chemical pesticides. Mix one part natural dish soap with two parts water for a simple carpenter ant killer. The soap breaks down ants’ protective coating, causing them to suffocate. Spray directly on ants and along their trails.
Essential oils containing D-limonene are toxic to carpenter ants and disrupt their breathing. Effective oils include peppermint, citrus oils, cinnamon, and lemongrass. Mix a few drops with water in a spray bottle and apply where you’ve seen ant activity. For best results, combine peppermint, clove, and citrus oils.
Create a vinegar spray using equal parts white vinegar and water. This disrupts carpenter ants’ pheromone trails and prevents them from following scent paths. Spray on entry points and let it dry naturally. Apply natural sprays every 24 to 48 hours or whenever you see carpenter ants.
8. Remove and Replace Moisture-Damaged Wood
Carpenter ants prefer wood with moisture content above 15%, so removing damaged materials can eliminate nests and prevent future infestations. Look for wood that feels soft, spongy, or hollow when tapped, especially around foundations, leaky pipes, windows, doors, and outdoor structures.
When replacing wood, use pressure-treated lumber designed to resist moisture and insect damage. Fix underlying moisture problems before installing new materials, or carpenter ants will likely return. Common moisture sources include leaky pipes, poor drainage, damaged gutters, inadequate ventilation, and missing weatherstripping.
If carpenter ant damage affects structural framing or load-bearing walls, contact a contractor before attempting repairs yourself. Professional pest control operators can help assess damage extent and determine whether wood replacement is necessary.
9. Eliminate Scent Trails and Entry Points
Carpenter ants rely on pheromone trails to navigate between nests and food sources. Spray entry points with diluted white vinegar and water, letting it dry naturally. Clean surfaces with cotton balls dipped in essential oils like tea tree, cedarwood, or citrus to mask pheromone trails.
Use silicone caulk to seal cracks and crevices around door and window frames, foundation cracks, utility pipe openings, and spaces between siding and trim. Even small gaps provide entry points for carpenter ants, so be thorough in sealing efforts.
Apply thin lines of diatomaceous earth or cinnamon around entry points to create natural barriers. Check sealed areas regularly for new cracks, especially after temperature changes. Replace worn weather stripping around doors and windows promptly.
10. Pour Boiling Water on Outdoor Nests
For outdoor carpenter ant nests, boiling water provides a direct, chemical-free elimination method. Boil several liters of water and exercise extreme caution when carrying and pouring it. Wear long pants and closed shoes for protection from splashes.
Pour boiling water directly into nest entrances and any other openings you can find. The water must be actively boiling for maximum effectiveness. Add natural insecticides, essential oils, or dish soap to enhance results.
You’ll likely need to repeat this process two or three times to completely eliminate the colony. Wait a day or two between treatments to see if ant activity continues. This method works best for accessible outdoor colonies in tree stumps, wood piles, or shallow ground nests.
11. Implement Comprehensive Moisture Control
Since moisture problems attract carpenter ants, controlling humidity and water issues is essential for long-term success. Repair leaks around pipes, faucets, chimneys, and skylights immediately. Improve ventilation in bathrooms, kitchens, and basements with proper exhaust fans.
Use dehumidifiers in damp basements and crawl spaces to keep humidity below 50%. Install vapor barriers in crawl spaces to prevent ground moisture from affecting wooden structures. Clean gutters regularly and adjust downspouts so water flows at least five feet away from your foundation.
Remove outdoor moisture sources like tree stumps, dying trees, and improperly stored firewood. Keep at least six inches of clearance between wood siding and soil. Trim tree branches so they don’t touch your house or roof, as carpenter ants use these as bridges to access buildings.
12. Call Professional Exterminators
Sometimes learning how to get rid of carpenter ants means knowing when to call experts. Contact professional exterminators if you continue seeing carpenter ants after several weeks of DIY treatment, or if you notice structural damage like stuck windows, spongy floors, or bulging walls.
Professional pest control operators use moisture meters and stethoscopes to locate hidden nests in wall voids. They have access to ultra-fine mist applications that penetrate wood more effectively than homeowner methods and can drill small holes to apply treatments directly into nesting areas.
Look for licensed operators with specific carpenter ant experience. Ask about treatment methods and follow-up visits. Most professional treatments include monitoring visits and guarantees. Don’t choose based on price alone, as thorough treatment and adequate follow-up service are more important than low cost.
Prevention and Long-Term Success
Once you’ve eliminated carpenter ants, prevent their return by applying residual insecticides around your home’s perimeter twice yearly. Store firewood off the ground and away from your house, checking it carefully before bringing indoors. Use inorganic mulches like stone or gravel in problem areas.
Inspect your home’s exterior monthly during warm weather for signs of carpenter ant activity. Check moisture-prone areas inside every few months and schedule annual professional inspections if you’ve had serious problems before.
The most effective approach to how to get rid of carpenter ants combines baiting to eliminate existing colonies, moisture control to remove attractants, and sealing entry points to prevent reinfestation. Start with identification and baiting, address moisture problems promptly, and don’t hesitate to call professionals if DIY methods aren’t working. Remember that carpenter ant damage happens slowly over years, so early action makes a huge difference in protecting your home.
