How to Get Rid of Carpenter Ants

A carpenter ant on a branch of tree

Carpenter ants. Just the two words seem intimidating. Images perhaps arise of a squad of them resembling Darth Vader’s stormtroopers marching in with relentless fervor. That makes how to get rid of carpenter ants near the top of the homeowner’s must-do list.

Are they as bad as all that? Well, when they’re hanging out in your garden, you’ll find them on the prowl for aphids. Carpenter ants farm aphids, eating their honeydew trails as they offer protection in return, so don’t consider your roses big fans. 

There’s also the damage they can do when all that relentless aggression gets let loose in your house. At worst, they could undermine the structure of your home. So we’re going to take a deep look at how to get rid of carpenter ants, both indoors and outdoors.

What Are Carpenter Ants?

Carpenter ants are the largest ants in North America. When mature, a western black carpenter ant colony will contain more than 50,000 individuals, of which up to 20,000 may be workers. There is generally just one queen whose body size is about 50 percent larger than the other individuals, who typically range from one-fourth to a little more than one-half inch in size.

Winged carpenter ants, also known as swarmers, are sometimes mistaken for termites. They leave the colonies to start their own colonies. Larger than the standard carpenter ant, they get up to three-quarters inch in size. And frequently, the first sign that carpenter ants are on hand locally is the sighting of swarmers.

Despite their name, carpenter ants don’t eat wood. They eat meats and sweets, making a garden the perfect locale for them to live, nibbling on insects (dead or alive) and plants. 

What they do to wood is burrow inside it, chew it up, spit it out, and leave behind what is called frass, the residue that builds up around a carpenter ant nest. As a result, they weaken and destroy wood by tunneling through it. 

How to Deal With Carpenter Ants in the Garden

Carpenter ant on a leaf in a lawn.
Photo Credit: Pxhere

Scout Out the Nest

Inspect the house and property for potential nest sites. It’s best to do it around sunset, when carpenter ants are most active. To get their attention, set out nontoxic bait like diced crickets or mealworms, which are available at pet stores and bait shops. 

Then observe the carpenter ants’ activities, following their trails back to the nest. With the nest located, inject an insecticide that contains pyrethroids into the nest. That may involve drilling, depending on the nest’s location. 

One note of caution: Do not spray liquids around electrical outlets or junction boxes. In those areas, insecticidal dust should do the trick.

Remove Water Sources

Carpenter ants love water. To combat them, remove water where it pools, denying the carpenter ant colony a reason to settle in.

Things to check on:

  • A leaky exterior spigot or hose.
  • Gutters that aren’t sealed and don’t funnel water away as they should.
  • Piles of leaves that can soak up and collect water.
  • A leaky exterior air conditioning unit. 

Carpenter ants will seldom set up camp far from a water source. By denying them the source, you are not too subtly suggesting this isn’t the place they want to be. 

Remove Wood Piles and Plant Debris

So, once having eliminated the water issues, you should rid your yard of loose piles of leaves and twigs and move firewood to a distance from the garden (and house) of at least 6 to 8 feet. 

Control the Aphid Population

Aphids infestation herd on Roses
Photo Credit: Lincoln Peh / Wikimedia Commons / CC BY 2.0

Carpenter ants have a symbiotic relationship with aphids (both insects benefit from the relationship). Aphids produce honeydew for the carpenter ants to eat, and in return, the ants offer protection, just like a farmer would protect their livestock. 

When aphids are abundant, there might be some carpenter ants nearby. Getting rid of aphids will make your yard less appealing to the carpenter ant colony. You can control aphids by applying insecticidal soaps or horticultural oil. 

Remove Rotting Wood

Is your wood raised garden bed or wood fence rotting? Carpenter ants consider these areas luxury living. When you detect rotting wood near your garden, promptly replace the wood so that carpenter ants will have to look elsewhere for shelter. 

How to Deal With Carpenter Ants in the House

Once inside, carpenter ants will leave a calling card just to say “Hi,” in the form of wood shavings. While they won’t eat the wood that comprises your house, they will burrow in, chewing it up as they create room for their nests. They discard the residue, which looks like well-ground sawdust, in small mounds at the entrances to their nests. When you see that, it’s time for action.

Seal Cracks and Entryways

So cracks in the foundation, broken screens or windows, and disintegrating weather stripping are all invitations into the house. And if given the opportunity, the existing carpenter ant troupe will make small entries larger, making it easy for all their buddies to come along.

Trim Trees and Bushes

And don’t forget that carpenter ants aren’t height-adverse. They will, if prompted, climb up the side of a house to gain entry. Even more than that, they will use trees with leaves and branches touching the upper reaches of a structure as an easy way to enter near the roofline. 

To combat this, you should keep trees (and tall bushes, too) away from direct contact with the house as much as possible. 

Apply Insecticides to the Nest

Carpenter ants dying of insecticide
Photo Credit: Duk / Wikimedia Commons / CC BY-SA 3.0

Some pros will set a trap for the carpenter ant to take back to the nest, allowing you to find the nest just by watching them. A bit of jam or jelly will appeal to their love of all things sweet. 

To go a step further, mix equal parts sugar and baking soda in a shallow dish. The sugar acts as a lure and will allow you to follow them back to their nest, and the baking soda will kill them naturally.

Once having located the nest, you can apply an insecticide directly into the nest, although you may need to drill holes in the wood to gain the best access.

Insecticides you can use to control carpenter ants: 

  • Sprays containing pyrethroids, such as permethrin or cyfluthrin
  • Dust containing disodium octaborate tetrahydrate or desiccants

What are desiccants? Desiccants are absorptive powders (diatomaceous earth or silica gel) that destroy insects by removing the protective, waxy outer body layer. This application causes the ant to dry up or desiccate. 

Of the desiccant dusts, diatomaceous earth is readily available in retail stores, but only a licensed pesticide applicator can apply silica gel. Desiccant dust is low in toxicity to humans and won’t lose its effectiveness over time as long as they remain dry. However, it’s best to avoid inhaling these materials because they can cause serious lung irritation.

Deprive Them of Food

So, although you probably do this in the general course of living in the house, it’s essential to keep food stored away. Problems may arise when it’s time to feed pets. One method is to serve pets their food at specific times and in quantities that the pets will leave little behind. 

Replace Water-Damaged Wood

One difference between termites and carpenter ants is that the ants don’t nest in dry wood. With water damage, however, the ants move right in, and the amount of damage they can cause is right up there with termite damage.

Replacing water-damaged wood is an essential part of keeping carpenter ants at bay.

How to Prevent Carpenter Ants 

Once you’ve cleared your home and garden of carpenter ants, execute some protective measures to ensure these critters don’t come crawling back. Here are some preventative methods that can help make your home and garden less attractive to carpenter ants:

  • Regularly wipe down counters 
  • Vacuum floors
  • Store all food in the pantry in airtight containers
  • Make sure to inspect window screens to ensure screens are intact
  • Store firewood away from the house
  • Trim bushes and trees so they don’t touch the house’s edge
  • Repair any water leaks
  • Caulk the foundation to make sure you have sealed cracks
  • Replace water-damaged wood
  • Control aphid populations
  • Promptly remove outdoor debris

Signs of a Carpenter Ant Infestation

Carpenter ants along the tree branches
Photo Credit: Pxhere
  • Piles of sawdust-like wood shavings in areas like baseboards, door jambs, and window sills.
  • Winged members of the carpenter ant nest hanging out in a house’s crevices or leaving behind their wings. 
  • Sometimes you can hear the ants producing rustling noises inside walls or hollow doors. Yikes!

Why is Controlling Carpenter Ants Important?

While carpenter ants aren’t a health threat, per se, and they seldom bite, they will go after the wood in your home and, left unchecked, can pose a threat to the house’s structure. That can manifest in warped ceilings, buckling walls, sagging floors, and damaged foundations.

Getting ahead of the problem can be a real money saver because those needed repairs, left untouched, can require a nice wad of cash to set straight.

FAQ About Carpenter Ants

What do carpenter ants eat? 

First, carpenter ants don’t eat wood; they chew through it. This is one thing that separates the carpenter ant from a termite because termites do eat wood. Both foragers and scavengers, carpenter ants will farm aphids for their honeydew and eat dead insects.

Are carpenter ants a danger to humans? 

There are times when carpenter ants will bite. It doesn’t happen often, but it can happen when they feel the need to defend themselves, typically when the nest is disturbed. The bites they inflict can be painful, and at times the carpenter ant may spray a defensive chemical known as formic acid into the wound, which may cause pain and, in some cases, nausea.

Where do carpenter ants like to live? 

These critters like to forage; indeed, they live to forage and stay close to their feeding grounds.
You will find them in:

Dead trees and tree stumps
Piles of leaves and twigs
Firewood
Deteriorating fencing and decks
Exterior structures where gardening work is done
Exterior steps

In the wood on houses, including window frames, door jambs, and hollow doors, particularly areas with untreated wood

When to Call a Pro

When you see signs of carpenter ants, inside the house or outside, it may not guarantee an infestation. However, it’s wise to take action. Without treatment, an infestation is likely coming.

Check out local pest control services with long histories of successfully combating these pests. They have the tools and materials to keep these pests from further inundating your life and home.

Main Image Credit: Ryan Hodnett / Wikimedia Commons / CC BY-SA 4.0

John Hickey

John Hickey

John Hickey, contributing writer at LawnStarter, has been around sports as a writer and blogger since the earth was young. He's worked at the Oakland Tribune and Seattle Post-Intelligencer, for AOL/FanHouse and Sports Illustrated. As he writes this, he looks out his window and sees a lawn badly in need of mowing.