Carpenter ant sawdust piled below a window sill; smooth carpenter ant galleries inside a wooden beam; winged carpenter ant on a wall

Signs of Carpenter Ants in Your Walls | Go Green

October 26, 2026•4 min read

Signs of Carpenter Ants in Your Walls: What a Forester Looks For

The clearest signs of carpenter ants in your walls are small piles of coarse sawdust, large black ants indoors in late winter or spring, winged ants coming out of a wall, and a faint rustling you can hear inside the wall when the house is quiet. If you see any two of these together, there's a good chance a colony is nesting in the structure of your home.

Why Carpenter Ants Matter

Carpenter ants chew tunnels through wood to make room for their colony and push the shavings out behind them. They go for wood that's already softened by moisture, then spread into sound wood nearby. A single nest does slow damage, but a colony left for several years can weaken sills, joists and deck framing. If you're seeing signs now, our ant control service starts with finding the nest.

Seven Signs to Look For

Sawdust piles. Look for small heaps of coarse, stringy shavings below window sills, baseboards, door frames or beams. It often has bits of dead ants mixed in.
Large black ants indoors early in the year. Seeing big ants inside in February or March, before it's warm outside, suggests they're living in the house.
Winged ants coming from a wall or ceiling. Swarms indoors in spring mean a mature colony is close by.
Rustling in the walls. Put your ear to the wall at night. An active nest can sound like faint crinkling paper.
Hollow sounding wood. Tap trim or framing with a screwdriver handle. Damaged wood sounds dull or papery.
Ant trails at night. Workers forage after dark, often along fences, hedges and power lines toward the house.
Damp wood. Any spot that stays wet, like a leaking window, a deck ledger or a bathroom wall, is where a nest is most likely to start.

Carpenter Ant Damage vs Rot or Termites

Wood damaged by carpenter ants has clean, smooth tunnels that look almost sanded, and the tunnels follow the wood's softer growth rings. Rotten wood is soft and crumbly without tunnels. Termite damage usually has mud or soil packed into the galleries. Termites are rare in the Lower Mainland, so tunnelled wood in a South Delta home is almost always carpenter ants.

The Main Nest and Satellite Nests

A carpenter ant colony often has a main nest outside, in an old stump, a dead tree or buried wood, and one or more satellite nests inside your walls. Workers travel between them. This is why spraying the ants you see indoors rarely works: the main colony keeps sending more. Finding both nests is the job.

What You Can Do Yourself

Fix leaks and moisture problems around windows, roofs, decks and bathrooms.
Cut back branches and shrubs so they don't touch the house.
Keep firewood, lumber and garden waste off the ground and away from the foundation.
Remove old stumps and rotting landscape timbers near the house.
Skip store bought sprays on the ants you see. They can scatter the colony into new nests.

When to Call a Professional

Call if you're finding sawdust, seeing winged ants indoors, or seeing large ants inside before spring. Carpenter ant nests are usually hidden inside walls, and locating them takes experience. The sooner the colony is treated, the less wood it damages.

Carpenter Ants in Ladner and Tsawwassen

South Delta's wet winters keep wood damp around decks, gutters and window frames for months at a time, which is ideal for carpenter ants. Homes backing onto trees, hedges or green space see the most activity, and calls peak from March through July. We serve all of Ladner, Tsawwassen and South Delta.