4 min read · Updated 2026-03-25
The clearest evidence
- Mud tubes about the width of a pencil running up foundation walls, piers or joists.
- Wood that sounds hollow when tapped and gives way easily when probed.
- Soil or mud packed inside damaged wood — a key difference from carpenter ants.
- Swarmers or discarded wings near windows, doors or light wells.
The indirect clues
Because subterranean termites work inside wood and avoid open air, the first thing many homeowners notice is cosmetic: bubbling or rippled paint on baseboards and trim, a section of floor that feels soft or spongy, a door or window that suddenly sticks, or a baseboard that separates slightly from the wall.
Any of these near an exterior wall, a slab edge or a basement is worth a closer look — especially in combination.
Where to check
- Basement sill plates, rim joists and support posts.
- Crawlspace framing and the underside of subfloor.
- Garage door frames and slab expansion joints.
- Porch posts, deck supports and any wood contacting soil.
When to get an inspection
If you find mud tubes, swarmers or damaged wood with soil in it, have the property evaluated before doing repairs — treating first prevents rebuilding into an active problem. Real estate transactions in New York frequently require a wood-destroying insect report as well.