Pest Control

Guide To Carpenter Ants Treatment And Prevention

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Hubert Miles

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Carpenter Ants

Carpenter ants are large ants (1/2 to 5/8 inches in length) belonging to the genus Camponotus. They live in forested areas, nesting in dead and damp wood. However, they will also move into your house and nest in any dead or damp wood they find therein.

Carpenter ants have mandibles adapted to burrowing through wood, and chewing their way through the wood in your home can cause significant property damage. If a carpenter ant infestation is left untreated, it can cause structural damage to a house over time.

Following them and eliminating their nest is the best treatment for carpenter ants. If the trail leads to a wall or baseboard, drill small holes around the entry point and puff boric acid powder through the holes. If the trail leads to an outside nest, treat the nest with a pesticide.

Prevent carpenter ants from entering your house by cutting back foliage that touches your home, moving wood stacks away from the house, filling cracks, fixing leaks, emptying drip trays, and maintaining outbuildings.

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Carpenter ants do not eat the wood, so you will find piles of sawdust near their excavation sites, indicating that carpenter ants are in your home. Other signs of carpenter ants in your home will be sighting these ants—their size makes them quite noticeable, and small holes appear in the wooden structures of your home.

When you notice these signs of a carpenter ant problem, you will need to take steps to eliminate these pests and prevent their return.

Treating Your Home For Carpenter Ants

Unfortunately, carpenter ants are persistent pests that can take a few tries to eradicate. One of the difficulties with getting rid of these insects is that carpenter ants make satellite nests. The queen is located in what is known as the parent nest. When this nest becomes overcrowded, the worker ants form satellite nests separate from the parent nest.

What this means to your attempts to eliminate the infestation is that you may destroy a satellite nest. Still, other nests, including the parent nest housing the reproducing queen, remain intact. But don’t despair, for there are steps you can take to get rid of carpenter ants, and if the problem becomes too extensive or too frustrating for you to handle on your own, there are professionals to whom you can turn for help.

It is easy enough to kill an individual carpenter ant. You can step on it or subject it to a blast from your household insect killer. However, you are unlikely to be bothered by a single carpenter ant.

Most professionals advise that finding and destroying the nest is the best method of extermination. Luckily, carpenter ants exhibit trailing behavior, meaning they lie and follow a scent trail between their nest and food sources. They will always follow these trails back to the nest, and you can follow them.

The trail will probably lead to a supposed dead end like a baseboard, a cabinet, or a wall. Either the nest is within the wall or just a part of their tunnel system. If you lose the trail, you should check areas such as behind the dishwasher or dryer, near the air-conditioning unit, sinks, bathtubs, etc.; anywhere there is high moisture content.

Once you find this point, you need to start by treating the area behind the wall, cabinet, or baseboard. Mike Potter, an Extension Entomologist at The University of Kentucky College of Agriculture, recommends drilling 1/8″ holes around the suspected nesting area and puffing a powdered insecticide like boric acid through these holes. As the powder disperses behind the wall, baseboard, or cabinet, it will kill the ants living or traveling through that area.

As you don’t know how large the space or nest is, you should treat up to six feet on either side of the ant’s entry point. Mike Potter also mentions carpenter ants are affinity for pipes and wiring, so be careful where you drill and what you put through the holes. You may not have killed all the ants the first time you do this, so leave the holes open and repeat until once or twice more.

Remember that you are puffing poison into your walls, so don’t go overboard. If the nest is there, the ants will die off. They will stop using this space if it is only part of their tunneling network.

It would help if you tried to find where they are entering your house from the outside. You can walk outside your house and identify where they are coming in. If you cannot find anything, they may nest in your house. However, if you find a trail of carpenter ants entering through the cracks around your drainpipes or wiring, they probably originate from an outside nest.

Follow the ants to their outside nest and spray or drench it with a chemical pesticide. Different states have different laws regarding pesticides and their use, so make sure you use legal ones for home use. Follow the pesticide manufacturer’s instructions, and be careful of using pets, children, and other sensitive individuals.  

If the carpenter ants have just started burrowing through your home, you can try replacing the most affected boards, etc. You will have to treat the damp spots as well. If the infestation went on for a long time before you realized it, you might need to hire someone to assess the structural integrity of your home.

Preventing Carpenter Ants From Entering Your Home

Carpenter ants are not naturally inside pests; however, if your home provides them with all they require (food, water, and damp wood for building nests), they will not avoid it just because it’s not a forest. To prevent carpenter ants from moving in, you should make your home undesirable to them and difficult to enter.

It would be best if you filled in all the cracks in your house’s structure, especially around your wiring and pipes. Carpenter ants can use these openings to enter your home, using the pipes and wires to traverse your house.

Fix all leaks that may be causing the wood in your house to become damp. These include leaks in the roof and plumbing. Ensure that drip trays for refrigerators, air-conditioning units, etc., are emptied to prevent overflow and damp formation.

Trimming the branches of trees that brush your house will help. Carpenter ants use these as bridges to your house. It also allows them access to less frequented parts of your home, such as the ceiling or attic, where they can cause much damage before you find them.

Stacks of firewood are prime spots for carpenter ants, particularly if uncovered and rained on frequently. Ensure your wood stack is kept well away from the house and keep it covered to discourage carpenter ants from moving in.

Carpenter ants also target wooden outbuildings. These are often poorly maintained and become the perfect spot for carpenter ants. Not only does this pose a structural risk to the outbuilding, but its proximity to your house may make it easy for the carpenter ants to move from outbuilding to home.

Keep wooden outbuildings well-maintained and raise their foundations to prevent dampness from seeping into the lower boards.


Carpenter ants are attracted to damp wood into which they burrow to create tunnels and nests. They are found in wooded areas but may move into houses if they find damp or dead wood in the structure of that house. Carpenter ants do not pose as big of a risk as termites to the structural integrity of your home unless the infestation is extensive and has gone untreated or unnoticed for a long time.

To treat carpenter ants, you must follow the trails back to their source. You can treat nests in wall cavities and other internal spaces with boric acid powder. You can treat nests in the yard with liquid pesticide drenches and sprays.

It may take multiple tries to fully eliminate the problem because carpenter ants form satellite colonies separate from the parent colony, where the queen resides and reproduces. Have patience and determination in your fight against these pests, but many extermination professionals will happily assist if it becomes too much for you.

You can take steps to prevent a carpenter ant infestation or re-infestation. You eliminate what attracts them and cut off their access to your house. They are attracted to damp and rotting wood caused by leaks, overflowing drip trays, exposed wood stacks, etc., and you can stop them from entering your house by sealing cracks in the foundations and walls and trimming back foliage that touches your house.

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Photo of author

Hubert Miles

I've been conducting professional home inspections since 2002. I'm a licensed Home Inspector, Certified Professional Inspector (CPI), Certified Master Inspector (CMI), and FHA 203k Consultant. I started to help people better understand the home inspection process and answer questions about homeownership and home maintenance.
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