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Carpenter ants

​​​During the year, you may notice more carpenter ants around gardens and homes. These large (6 to 10 mm) black ants often become pests in their search for food. They eat both animal and plant matter. Carpenter ants can damage wooden structures by eating their way through the wood to make tunnels for nesting.

Where do they live?

Outdoors, carpenter ants live in places like dead tree trunks, logs, and fence posts. They prefer moist, decaying wood. They might make nests in wooden steps, wooden sills, and around porches.

Carpenter ants can enter a home in many ways:

  • through windows
  • through holes in foundations
  • along power and telephone cables
  • along tree branches
  • by firewood that's brought inside

If you find carpenter ants in your home, it could mean that you have a moisture problem or the ants are eating away at the wood your house is made of. If you see sawdust-like shavings and a lot of carpenter ants with wings inside your home, it usually means you have a nest inside your home.

How do I control them at home?

Do the following to control carpenter ants in your home:

  • Remove all decaying or infested wood from around buildings. Store firewood away from the sides of a building.
  • Make sure the humidity in the building isn’t too high.
  • Keep the floors clean. Sweep regularly to clean up food crumbs.
  • Use insecticides (baits, sprays, or dusts) on the nest and area around the nest. Read the label closely. Chemical control only works when you also use other control methods.

When should I hire a professional?

If the problem is bad, it’s best to hire a certified pest control professional. Do your research and choose one you can trust.

The professional should be able to tell you what’s causing the pest problem and come up with a plan to get rid of the pest. The professional may need to make several visits, and it may take days or even weeks. Tell the professional if you have children or pets.

If you rent, your landlord must, by law, keep the home pest-free and hire a professional as needed. If your landlord doesn’t correct the problem, call Health Link at 811 to register a complaint for a health inspector.

To learn more, contact Alberta Health Services Environmental Public Health​.

Current as of: April 26, 2021

Author: Environmental Public Health, Alberta Health Services