Carpenter ants, or camponotus, build their colonies in wood. We will tell you how to find their nests and distinguish them from termites. You'll know the best methods of getting rid of carpenter ants according to the scientists and find the 18 Best carpenter ant killers: poison baits, killer sprays, foams and dusts.
If you are looking for the most effective treatment, scroll to the end where we will present 2 concentrated insecticides used by professional exterminators. Neither the carpenter ants nor other household pest insects will be able to withstand such measures.
Table of Contents:
- Know The Enemy
- Scientific Methods of Getting Rid of Carpenter Ants
- How Ant Killers Work
- Top-18 Best Carpenter Ant Killers
- Natural & Organic Carpenter Ant Killers
- Carpenter Ant Baits (Poisons)
- Carpenter Ant & Termite Killers: Spray, Foam and Dust
- Best Concentrated Insecticides and Sprays
- Professional Insecticides
- Carpenter ants are black and fairly large (up to ½ inch). Usually their appearance in the spring next to a tree or a structure of wood signifies the proximity of their colony.
- Some may confuse them with termites, but carpenter ants are larger, have a different shape of antennae and body. Unlike termites, ants do not feed on wood, but make a colony in it instead. Crushed wood is removed from trails and paths outwards. Sawdust can lie openly or piled behind a wall.
- Carpenter ants DO NOT create mounds in the soil. They settle in wet and dry wood preferring wet wood, which is why their nests can be found in living trees and wood, near water sources in bathrooms and around basins. They are not visible from the outside since the wood becomes fragile but retains its shape.
- To find a nest, you can try screwing a hole with a screwdriver or knocking with a handle and listening as the ants will respond with a peculiar quiet rustle. Remember to never touch them with your bare hands as the workers have strong jaws and bite readily if they are handled.
- Fortunately, carpenter ants are not as destructive to wooden houses and furniture as termites are, but the scale of destruction is not always visible since they create a maternal colony with a queen and thousands of workers and a few satellite ones with a large number of workers and no queen.
The only way to get rid of carpenter ants is to destroy their nests. It is a difficult task given that their colony is usually located in a secluded spot.
To find their nest, feed the insects with something sweet, such as honey. Once an ant has taken the food, it will hurry back to its nest and you’ll be able to follow the trail.
The insect will hide behind the baseboard, in the closet or anywhere else where its colony is located. For complete extermination, it is crucial to penetrate into the void and the passages of the nest.
8 Steps to Destroy Carpenter Ant Nest
- Fix any roof or water pipe leaks, remove other sources of moisture, exclude contact of the wood with soil or mulch where possible, don’t let the trees touch your house, seal any holes and cracks in the foundation, especially around the wiring, and do not store firewood in the house or in the garage.
- Since ants have a “sweet tooth,” reducing the number of insects that produce honeydew (substance secreted by aphids) might control ants around structures, as state the University of California specialists.
- Use boric acid. The University of Kentucky experts explain how it’s done: «Treat wall voids and other hidden spaces where ants are entering by carefully drilling a series of small (1/8 inch) holes and puffing boric acid into the suspected nest areas. The boric acid powder will disperse in the hidden void and contact and kill the ants. If you suspect the nest is in a wall, drill and treat at least 3-6 feet on either side of where ants are entering to maximize the chances of contacting the nest».
- Using slow acting baits is the most effective way to destroy the colony. This is critical, because only about 10% of the ants are out foraging at any one time, and the remaining 90% are in the nest. The ants must be able to take a piece of poisoned bait and carry it to the nest to share with its co-habitants and the queen. Killing the queen means defeating the entire colony.
- Just like with any other species, the food preference of the carpenter ants appears to change on a seasonal basis. The University of Ohio scientists are convinced that the larvae require protein-based foods, so it is more helpful to use protein-based baits for getting rid of larvae.
- Aerosol spray nest treatments can be effective. Insecticidal vapors can spread within the wood to penetrate inaccessible areas of the nest, aiding in colony eradication.
- Sticky traps are far less effective. Their use is justified only by the need to protect a specific object, for example, a fruit tree from the effects of insects.
- Carpenter ants are finicky so you’ll have to provide them with a wide variety of different kinds of poison baits: sugar and protein-based.
First attract them to a nontoxic food source like sugar milk, cherry or diced crickets or mealworms. After the ants start feeding, replace the nontoxic food source with several different toxic baits, and let them choose the one they prefer.
The University of Minnesota experts claim that carpenter ants are very fond of the protein-rich tuna, which is why they are so often seen eating cat food made of fish. Add some pieces of fish to the poison lying around and wait for the results.
|Type||Active Ingredients||Action||Best Use|
|Liquid insecticide||Bifenthrin, Gamma-cyhalothrin, Deltamethrin||Kills on contact and creates a protective barrier around the house.||Use outdoors or indoors. Pour into mounds, treat foundations and spray in the insects' activity areas.|
|Granules||Acephate, hydramethylnon||They destroy an outdoor colony and prevent new pests from appearing.||Use outdoors for broadcast treatment, pour it around the mound and along the trails.|
|Foam and sprays||Fipronil||Will kill an inaccessible colony within a few days.||To be sprayed on nests in the walls.|
|Poison baits (bait stations)|| |
|The most effective method that can eliminate the entire colony. It is effective within 3-5 days (fast-acting), 1-5 weeks (slow-acting).||Use indoors or outdoors. Ants are finicky and they change their preferences often so you will likely have to switch bait types several times.|
|Diatomaceous Earth||Organic insect killer||Contact action: the particles cut the insects' exoskeleton and cause dehydration.||Use indoors, spray along the trails and in the insects' activity areas.|
|Boric acid (dust)||Low-toxic insect killer||Slow-acting stomach poison.||Use indoors, spray along the trails, down the cracks and shelters.|
|Limonene||Citrus essential oils ingredient||Impacts the CNS, causing paralysis and death of insects.||Can be used near food.|
|Oils and Natural sprays||Clove, peppermint, geranium, cinnamon leaf oils||Contact action and certain repelling effect.||Сan be used for treating any areas and creating a protective barrier around your house.|
|IGR||Pyriproxyfen||Highly effective: sterilizes the queen and therefore will remove the colony completely.||A very slow-acting product (is effective at least after a month), so be patient.|
There are many universal insecticides available on the market suitable for dealing with ants, but not all of them are helpful against carpenter ants.
We have selected 18 organic & insecticidal products that contain active ingredients recommended by scientists: Diatomaceous Earth, borax, abamectin, fipronil, hydramethylnon, bifenthrin, cyfluthrin, cypermethrin, deltamethrin, lambda cyhalothrin, permethrin, carbaryl (Sevin), diazinon, and chlorpyrifos.
As usual, we’ll begin with organic products, and then we will move on to the most effective baits and killers, and end our review with powerful insecticides.
Safer Brand 51703 Diatomaceous Earth Crawling Insect Killer
Diatomaceous earth is a universal non-toxic control product for insects and arachnids. The remains of diatom algae are crushed to a certain size, when they turn into an acute insecticidal weapon.
The edges of the particles of diatomaceous earth cut the chitinous cover of the insect and damage it, causing the strongest lethal dehydration.
The product is safe for humans and pets and is not capable of damaging their skin. It is sold in a 4-pound package. Sprinkle the places of congestion and migration of ants with this powder.
Price: ~$9.47 Check the current price
PestGuard Zap-a-Roach Boric Acid Roach & Ant Killer NET WT. 1 LB. (454 gms) - 2 pack
A boric acid tube is a yet another traditional treatment. Two 16-oz boric acid tubes cost ~$10.89. This acid has long been used as an antiseptic in medicine. Over time, the remedy has been replaced by stronger antiseptics, and boric acid was still used when getting rid of ants.
It acts as a slow-acting stomach poison. The powder is placed in the cracks, behind the skirting boards, and sprayed through the nest entrances.
Boric acid powder is a real homemade ant treatment that has been used for ages because it is cheap, simple and quite effective. Still, keep in mind: whilst the working ants will bring the powder on their legs to the nest, there is no guarantee that it will reach the queen.
Price: ~$10.89 (2-pack) Check the current price
Clove Essential Oil
Clove essential oil for ~$15.95 is not an insecticide, but the scientists have confirmed its insect-repelling properties caused by its active ingredient, eugenol.
Clove oil is to be dissolved in a moderate amount of water and sprayed in places where there are many ants. Remember to shake the mixture regularly so that the oil remains afloat. Caution! Essential oils can be hazardous for pets, especially cats, pregnant women and small children. Don’t use pure oil.
Price: ~$15.95 Check the current price
Poison baits are most effective. They work as follows: a worker ant picks up poison to contaminate the entire colony including the queen.
Borax-Based Terro Liquid Ant Bait
Although only common household ants are listed on the label, the University of Arkansas experts name the active ingredient of Terro Ant Killer, sodium tetraborate decahydrate (borax) as one of the insecticidal baits that have shown promise in controlling carpenter ants.
Poison bait contains borax (boric acid) that acts as a slow-acting stomach poison. Once it reaches an ant’s digestive system, it impacts metabolism and interferes with the absorption of nutrients, causing death by starvation.
Terro outdoor baits contain the same active substance, borax, but the traps have been adapted for outdoor use. The product is sold in packs of 6 poison bait stations. A station should be installed in the ground or on the surface. The customers commend this bait. It is available as stakes that are pinned to the ground as well.
Price: Terro for Indoors ~$4.72 Check the current price
Price: Terro Outdoor Baits ~$11.53 Check the current price
Price: Terro Outdoor Stakes ~$19.99 (2-pack) Check the current price
Terro sells best-selling baits, but other brands use different ingredients that are also recommended by the entomologists: Maxforce by Bayer (fipronil), Advance (Abamectin) and Amdro (Hydramethylnon). Ants are very finicky so many users buy a few different baits to match the various tastes of fastidious carpenter ants.
Maxforce Carpenter Ant Bait Gel-1 (Bayer)
This fipronil-based bait for ~$23.93 comes in a syringe and is made for eliminating carpenter ants. They love sugar and moisture, so Maxforce is most saturated with them for better attraction. Just like other liquid baits, this gel should be placed in the areas of activity of ants and near the nest.
The product can be used both indoors (including hospitals, restaurants, schools and other public places) and outdoors. Fipronil is relatively slow-acting poison, so the effect can be expected in about 3-5 days.
Carpenter ants are very fond of tuna, so they can often be found eating cat food made of fish. The users give valuable advice on making the sugar-based Maxforce bait as effective as possible: you need to lay some tuna leftovers in the right places and you will get a combo-bait. Read all customer reviews to find more tips about using it.
Price: ~$23.93 Check the current price
Advance Carpenter Ant Bait Granules
This fishy bait is based on delayed-action insecticide Abamectin. Once in the digestive tract, abamectin depresses the pests’ neuromuscular activity: “Visible activity, such as feeding and laying the eggs, stops shortly after exposure, though death may not occur for several days” (IPM).
These ~$26.29 granules can be used both indoors and outdoors for removing carpenter ants as well as Acrobat, Bigheaded, Pavement and other ants.
Sprinkle the bait in the ants’ activity areas and check where they carry it to find even several nests at once. The users recommend combining Advance with Maxforce as it is the combination of different baits that will lead to the best results.
Price: ~$26.29 Check the current price
AMDRO Kills Ants Bait Stations, Indoor
A ~$5.33 pack contains 4 stations with hydramethylnon-based baits. They are slow-acting baits, meaning that the chance of killing not only workers but also the queen is very high.
According to the manufacturer, the process will take about two weeks. The stations are for indoor use only as they can work for three months and should be replaced with new ones when necessary.
This might seem too long for some, but the scientists name slow-acting baits as the most effective means of getting rid of ants. It is quite economical as well as a single bait station costs less than $1.5. In addition, the manufacturer guarantees a refund in case the product proves ineffective.
Price: ~$5.33 Check the current price
Aerosol sprays, foams and dusts that could be sprayed deep down the nest are most effective against carpenter ants. Such products act as fast-acting poisons killing on contact.
Best Foams and Dusts
TERRO 16 oz. Carpenter Ant & Termite Killer Aerosol Spray
This ~$8.99 killer spray’s active ingredients are chemicals-pyrethroids: tetramethrin and deltamethrin.
A thin and long nozzle will allow spraying this foam type of liquid deep into the wall cracks, corners, hard-to-reach places, and holes in wooden structures where insects have already settled, and directly into the nest itself.
Terro promises to ensure not only a quick killing effect, but also residual control over carpenter ants and termites for up to four weeks - and the users confirm this: “I keep finding hundreds of dead/dying carpenter ants weeks after spraying this on the rafters in my basement. It has some pretty damn good staying power.”
Use Terro both indoors and outdoors even if the pests have infested the trees in your garden: just spray the trunks around the whole circle with this spray and pour it into the holes filled with ants.
Price: ~$8.99 Check the current price
Termidor Foam is a universal fipronil-based wood destroying insect treatment that is effective against carpenter ants, termites and other pests. Similar to other products, this foam is to be locally sprayed in the area of the insects’ activity, wooden holes and deep down the nest.
An ant colony can die of foam action within a day or two. Moreover, it is very dense and the ants won’t be able to overcome this barrier and survive. Although the product is quite expensive and costs ~$26.48, users unanimously accept that it is effective and more affordable than hiring professional exterminators. Its 4.7 out of 5 stars rating can prove this.
Price: ~$26.48 Check the current price
TERRO T600 Ant Killer Dust
A deltamethrin-based (a fast-acting rainproof component) waterproof dust is yet another product of the Terro line. It is versatile as it promises not only to remove carpenter ants, but also to kill on contact boxelder bugs, cockroaches, crickets, firebrats, spiders, ticks, wasps and silverfish at the price of only ~$7.49.
It can be applied anywhere where there are pests (both indoors and outdoors) and on any entrances to your house. To avoid making a mess, use a paint brush or a duster such as Harris Powder Duster for a ~$9.99.
The product is popular as it is one of the most accessible contact poisons and most of the users are satisfied with its effect: “This Terro Dust is the only ant killer that has been effective for me against Carpenter Ants. Within 3 days of placing this powder, the ants all appeared to be dead, dying or gone.” Read over 500 customer reviews on Amazon.com to decide for yourself whether it is worth buying.
Price: ~$7.49 Check the current price
Bayer Advanced 700310 Carpenter Ant and Termite Killer Plus Concentrate, 32-Ounce - For Outdoor Use Only
If you have noticed some carpenter ants outdoors that have not yet penetrated your house, then this concentrated B-Cyfluthrin-containing insecticide will help them kill on contact and 75 other types of insects and protect your house from infestation.
It is to be dissolved in water and applied on lawn, landscape, foundation, trench, deck and patio, wood piles, and home structures and poured down a mound. This is a very economical option as a ~$19.87 32 oz bottle will be enough to cover 21,000 sq ft for lawn pest treatment and 10,500 sq ft for wood destroying pest treatment.
Such powerful treatments are not very popular with regular people, but those who have had a chance to test it, claim that it kills pests and can even serve as a preventive measure: “Works great, I spray around the foundation of the house twice a year, the only bugs that I see are dead. I did not spray one year, and the carpenter ants and the termites tried to move back in. Once I sprayed, they were gone.” Some users complain that treatment takes too long, though.
Price: ~$19.87 Check the current price
Ortho Home Defense MAX Insect Killer for Indoor & Perimeter RTU Wand
This insecticide contains bifenthrin, which is a fast-acting component and a 1.1 canister is available for ~$26.92. It is ready to use on a dry surface or down the nest.
The product is lethal for over 130 insect species, including carpenter, fire, lawn, argentine, pavement, pharaoh, pyramid, and red/western harvester ants. In addition, Ortho creates a barrier protecting your house for up to a year, and the lot for up to three months.
Judging by the reviews, it can reduce the number of ants in a day, but you may resort to repeat use if necessary as if the queen survives, the colony can be revived.
Price: ~$26.92 Check the current price
Spectracide HG-95830 Triazicide Insect Killer for Lawns & Landscapes Concentrate, Ready-to-Spray
This ready-to-use spray contains such active ingredients as gamma-cyhalothrin and should be attached to a hose for spraying, it costs from ~$6.88. The manufacturer claims that this spray kills over 250 insect species including ants.
As the Amazon.com customers state, the product doesn’t act on all types of insects, but it works against carpenter ants as the spray ensures up to three months of residual control. The product is for outdoor use only.
Price: ~$6.88 Check the current price
Sevin Concentrate Bug Killer
This must be the most eco-friendly insecticide listed (it contains Carbaryl) as it can be used for removing over 100 insects and sprayed even on vegetables, fruit and ornamentals.
Its active ingredient, Carbaryl’s, advantage is that it does not accumulate in humans’ or pets’ bodies and is harmful even for small pets, such as rabbits. A concentrate in the bottle is to be dissolved in water and used for treating contaminated trees and wooden structures with a sprayer.
Price: ~$9.79 Check the current price
Suspend Sc Insecticide
A pint of the product containing 4.75% deltamethrin costs ~$39.97. The insecticide is to be dissolved in loads of water (up to 64 gallons), so you’ll spray a large area with it. It can be used both inside and outside.
The product is odorless and highly rated by the Amazon.com customers. Experienced homeowners spray the foundation and entrances, such as doors, windows and cornices and forget about the existence of the carpenter ants.
They recommend that you not relax though and to watch the trees outside as they can easily become the hotbeds of carpenter ants. They can penetrate the house even through the roof if any tree branches touch it. Read over 700 customer reviews on Amazon.com to learn more.
Price: ~$39.97 Check the current price
This universal insecticide contains 7.9% of bifenthrin, a powerful pyrethroid that promises to deal with over 75 insect species. It is sold as a concentrate for ~$35.66 that should be mixed with water.
The product will act for up to three months provided it is properly used on dry surfaces both indoors and outdoors.
Talstar’s high rating of 4.6 out of 5 stars on Amazon.com is fully justified as the users recommend spraying the foundation of the building along the outer perimeter to create an additional killing barrier against the ants attempting to penetrate the house. Read over 1600 customer reviews to find more helpful tips.
Caution! This insecticide is toxic for aquatic plants and animals; you shouldn’t use it near bodies of water. When spraying it, wear protective gloves and avoid contact with skin and mucous membranes. Once the treated surfaces are dry, they become safe.
Price: ~$35.66 Check the current price
18 Carpenter Ant Killers Comparison Chart
|Product||Type||Active Ingredient||How To Use It?||Price|
Safer Brand 51703 Diatomaceous Earth
|Contact activity||Diatomaceous Earth||Pour it along insect trails.|
PestGuard Zap-A-Roach Boric Acid (2-pack)
|Slow-acting stomach poison||Boric acid||Pour it along insect trails, in the corners, floor cracks, under kitchen appliances, wooden furniture etc.|| |
Clove Essential Oil
|Contact activity||Clove Essential Oil||Dissolve in water and draw a line along the perimeter of the house or yard.|
TERRO T300 Liquid Ant Baits
|Slow-acting||Borax||Place several bait stations near the places where there are lots of insects, or their trails.|| |
Terro 1806 Outdoor Liquid Ant Baits
|Slow-acting||Borax||Place several bait stations near the places where there are lots of insects, or their trails.|
Terro T1812-2 Outdoor Liquid Ant Killer Bait Stakes
|Slow-acting||Borax||Stick the stakes into the soil near your house and near the spot of ants’ activity.|| |
Maxforce Carpenter Ant Bait Gel-1
|Relatively slow-acting poison||Fipronil||Place this bait on the trail and near the entrance to the ants’ nest.|
Advance Carpenter Ant Bait Granules
|Fast-acting||Abamectin||Pour it along insect trails and near the entrance to the nest.|
AMDRO Kills Ants Bait Stations
|Slow-acting||Hydramethylnon||Place several bait stations near the places where there are lots of insects, or their trails.|| |
TERRO 16 oz. Carpenter Ant & Termite Killer Aerosol Spray
|Fast-acting||Tetramethrin % deltamethrin||Spray it in cracks in wood and pour down a mound.|
|Relatively slow-acting poison.||Fipronil||Spray it in cracks in wood and pour down a mound.|
TERRO T600 Ant Killer Dust
|Fast-acting||Deltamethrin||Pour it along insect trails, in the corners, floor cracks and down a mound.|
Bayer Advanced Carpenter Ant&Termite Killer
|Fast-acting||B-Cyfluthrin.||Dissolve in water. Apply on lawn, landscape, foundation, trench, deck and patio, wood piles, and home structures; pour down a mound.|
Ortho Home Defense MAX Insect Killer
|Fast-acting||Bifenthrin||Spray it indoors in places where there are lots of insects. Outdoors: spray along insect trails and pour down a mound.|
Spectracide HG-95830 Triazicide Insect Killer
|Fast-acting||Gamma-cyhalothrin||Attach to hose and spray it in places where are lots of insects. Pour down a mound. For outdoor use only.|
Sevin Concentrate Bug Killer
|Slow-acting||Carbaryl||Dissolve in water. Spray it in places where there are lots of insects. Pour down a mound.|
Suspend Sc Insecticide
|Fast-acting||Deltamethrin||Dissolve in water and pour down a mound or spray it indoors in places where there are lots of insects.|
|Fast-acting||Bifenthrin||Dissolve in water and spray on the spots of ants’ activity. Pour down a mound.|