Field plate · Camponotus spp.
Carpenter ant
Large black ants that excavate damp wood. Spring swarmers and piles of coarse sawdust are the tell.
Plate 10 of 28. Drawn in profile to the identification marks named below; the scale rule is a drawing convention — sizes are given in the text.
Identification marks
Workers 6–13 mm, mostly black with a single pinched waist segment and evenly rounded thorax profile. Winged swarmers appear on warm spring days. Excavated galleries are clean and smooth, unlike termite workings.
Look-alikes it is confused with
Other large black ants (field ants, which do not excavate houses) and termite swarmers — ants have bent antennae, a pinched waist, and unequal wings; termites have straight antennae, a broad waist, and four equal wings.
Where it hides in a house
Wood already softened by water: window and door frames, sills over damp foundations, deck ledgers, porch posts, bath surrounds, and the foam insulation of additions. A nest indoors usually means a leak above it.
Health & property risk, stated plainly
Structural, given time. They do not eat wood — they quarry it — but a mature satellite colony in a sill or header weakens it, and the moisture that invited them is damaging the wood regardless.
What actually works
Find and fix the moisture source; replace punky wood; trim branches off the roof; then treat the nest itself — located by following night-time foragers — with bait or a direct void treatment. Monitoring through the spring season confirms it.
What doesn't
Spraying the trail on the counter. It kills foragers, leaves the nest in the wall, and can split a colony into satellites that are harder to find.
When to call a licensed pro
Call a pro when sawdust recurs, swarmers emerge indoors, or activity is in a sill, header, or other structural member — and fix the leak either way, or the next colony is already invited.