Carpenter Ants control in Canada
Large black ants that excavate wood — damage adds up quietly.
How to identify it
Large black ants, 6–13 mm, often seen at night. Winged swarmers appear in spring.
Signs of an infestation
- Coarse sawdust (frass) below trim, sills or beams
- Faint rustling inside walls
- Large black ants indoors in winter — a sign of an indoor nest
Is it dangerous?
They don't eat wood, but galleries excavated over years weaken structural timber.
Can I handle this myself?
DIY is not recommended
Spraying visible ants leaves the parent nest intact.
When to call a professional
Call a professional whenever you see frass or large black ants indoors.
Any pesticide used in Canada must be registered here and applied exactly as its label directs. We don't publish application instructions.
Typical professional treatment
Nest location, targeted injection of galleries, perimeter treatment and moisture recommendations.
Visits: 2 visits, plus a season-end check
How to keep them from coming back
- Fix roof, gutter and plumbing leaks
- Replace water-damaged wood
- Keep mulch and wood piles off siding
- Trim branches touching the roof
What carpenter ants treatment costs
Typical treatment in your area
$300–$700
2 visits, plus a season-end check
Severe infestations, multi-unit buildings or multi-visit protocols can cost more. Estimates are illustrative sample data.
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