Carpenter ants are notorious for freaking out homeowners who think their house is about to fall down. Luckily, unlike termites, carpenter ant cannot digest wood, but rather excavate burrows called “galleries” for nesting.
Carpenter ants can be hard to get rid of without professional grade chemicals because they can have multiple nests, some that may be far away from your house. But if you read this article, you’ll have a good idea of your options for home remedies to control carpenter ants naturally.
1. How to Identify Carpenter Ants
Carpenter ants are distinctive, because they’re larger than pavement ants, odorous house ants, and other common home invading ants.
- Carpenter ants species’ workers are not all one size (polymorphic), other common pest ant species’ workers are all one size (monomorphic).
- The smallest workers are usually about the size of a grain of rice, or larger.
- Most carpenter ants are shiny black, or reddish black.
- Carpenter ants appear as large black ants, trailing “lazily”, one-by-one on sunny walls of your house, along utility cables, and nearby trees. Small ants form dense, highly active trails sometimes 3-4 ants side-by-side.
2. Eliminate Carpenter Ant Habitat
Carpenter ants love moist, softened wood because they can easily excavate nest galleries. If you are seeing carpenter ants in your house, that could indicate that there is a moisture issue somewhere in the house.
- Start by inspecting your windowsills, where moisture naturally condenses, drips and can cause windowsills to rot.
- Check around sinks, showers, and toilets for any evidence of leaks or water damage.
- Water damage often manifests as peeling, shrinking, curling, discoloration, or a soft, rotten appearance.
- Make sure your gutters are draining properly, and carrying water away from the home.
- Make sure there’s no mulch or soil contacting your windows, doors or siding.
- Remove any excess wood storage or yard debris outside.
- Inspect your crawlspace for standing water.
- It’s super important to keep tree branches and shrubs trimmed away from the house. Since carpenter ants love to climb, you might also need to remove string lights attached to the house to prevent them trailing onto your siding.
- Review our guide on naturally eliminating pest habitats around the home for ants, rodents & more.
3. Use Botanicals to Repel Carpenter Ants
Many natural insectide sprays contain essental oils like peppermint, cinnamon, thyme, etc that kill on contact and leave strong repellent odors. Typically, exterminators do not recommend using repellents to kill individual ants. Ant colonies have a tendency to reorganize and persist if the entire colony isn’t destroyed.
- But if you only see a few carpenter ants outside, spray the ant trails, along your perimeter, foundation, and around cable junctions with any botanical insecticide labelled for ants.
- Repeat the spray every 24-48 hours, or whenever you see carpenter ants.
- If you have flowers & foraging pollinators around your home, or if you see carpenter ants inside, you’ll want to try the next suggestion below:
4. Diatomaceous Earth for Carpenter Ants
Diatomaceous earth is highly lethal to ants & other arthopods because it desiccates their bodies.
It requires less frequent application than botanical sprays, which reduces the risk of drifting onto bees & beneficial insects.
The trick is to get the right amount, in the right places, while taking extreme care not to inhale any or expose your family to the dust.
- Chronic exposure to silica dusts like diatomaceous earth, can cause silicosis, an irreversible lung disease.
- Always wear a respirator and gloves when handling diatomaceous earth (DE).
- Use a bulb duster or bellows duster to apply DE directly into wall voids where carpenter ants are nesting.
- Apply only a very thin layer, too much DE will act as a repellent, and may cause them to move to different areas in your house.
- Do not leave any DE dust exposed. Dispose of any visible excess dust by wiping up with a damp paper towel.
5. Boric Acid for Carpenter Ants
Boric acid is a well known natural pesticide that poisons ants’ stomachs & nervous systems, and kills them.
It is also sold as a dust, that can be applied like DE– with the same technique mentioned above.
- Again, wear a respirator & gloves when applying boric acid to be safe.
- In general, boric acid is low-toxicity, but can cause skin irritation if touched, and nausea, vomiting, and other gastrointestinal issues if eaten.
- Only apply boric acid after doing a thorough inspection.
- Apply into crevices, cracks, and wall voids where you see carpenter ant activity.
** Soffit voids, window sills, and any areas that have visible water damage are places where carpenter ants frequently are found.
6. Granular Baits for Carpenter Ants
Many of us are familiar with using liquid baits for sugar ants in the home. However, since carpenter ants range further, the liquid bait they drink rarely gets a chance to make a dent in the colony.
Granular baits are carried by the carpenter ants back to the colony. These can be part of an effective strategy to keep their populations under control around your house, garage or shed.
- Inspect for ant trails on a warm afternoon.
- Place granular bait along active ant trails, around trees, shrubs, mulched areas, and sunny sides of the home according to the label.
- Allow 3-4 weeks for the bait to take effect, and re-apply monthly through autumn until carpenter ants are under control.
- Try DIY ant baits indoors to treat the carpenter ants inside your house
Click to Get Rid of Ants. 
Natural Carpenter Ant Control
Controlling a heavy infestation of carpenter ants with only natural ingredients would take a lot of time and dedication. It’s important to evaluate your goals.
Are you trying to limit your exposure to harmful substances? Is your home a haven for pollinators & beneficial insects? Or are you trying to eliminate the use of synthetic active ingredients?
It may be lower-risk for you to hire a careful professional than inhale a bunch of boric acid dust as you bumble through a DIY treatment.
But if you have a pollinator garden planted right next to your foundation, you should be very careful when hiring an exterminator. While very safe for humans & mammals, synthetic products created for carpenter ant control can be very risky for honeybees and other pollinators if sprayed near flowers.
A pest control company that’s State licensed and Green Shield Certified will be able to help you with your goals, and create a customized treatment that will protect you, your family, pollinators & the environment.
Need help with carpenter ant control around Portland, Oregon today? Contact Pest & Pollinator.
Curious whats sets us apart? Learn more about Pest & Pollinator here.
Feature photo credit: Robert Webster / xpda.com
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