Carpenter ants in wood framing
moderate 1–3 h
Tools: flashlight (red filter or dimmed for night watching), small brush, caulk gun, pruning saw · Materials: carpenter-ant gel or granular bait (sweet and protein types), silicone caulk, borate wood treatment for exposed framing
Steps
- Watch at night: carpenter ants forage after dark, so sit quietly with a dim light near the frass or the kitchen and follow the workers back — the trail ends at the nest entry.
- Follow the trail outside too: a dead stump, a woodpile or a rotting fence post within 30 m (100 feet) is often the parent colony, and the indoor nest is a satellite.
- Put out both sweet and protein baits along the trail, not on it; do not spray the trail with a repellent — the ants relocate and the colony survives.
- Give the bait two to three weeks and refresh it; the workers carry it home and the colony declines quietly.
- Caulk the entry holes and the gaps around pipes and cables where the trail entered, and prune branches touching the house.
- Treat any exposed framing you can reach in the basement or attic with a borate solution once it is dry; it stops future nesting in that wood.
Stop and call a pro if
- the trail leads into a wall you cannot open or the frass keeps appearing after three weeks of bait
- the colony is in a load-bearing beam, the roof structure or a sill plate
- there are winged ants swarming indoors — the colony is mature
Rules in the US: Non-repellent termiticide-class liquids are restricted-use in many states; baits are what a homeowner may use.
What a pro does that you can't
A pest-control technician uses non-repellent liquids and professional baits that reach the whole colony, and confirms with a follow-up that the satellite nests are gone.
DIY cost: $20–50 in baits and caulk