Carpenter ants in wood framing — Leiden, Zuid-Holland

Carpenter ants don't eat wood — they excavate it to create nesting galleries, leaving behind smooth, clean tunnels and small piles of frass (sawdust-like debris). They're attracted to wood softened by moisture, so their presence usually signals a moisture problem somewhere in the structure — around leaking pipes, roof flashings, or window frames. A single mature colony can contain 10,000–50,000 workers, and satellite colonies throughout a house can cause significant structural damage over years. A pest control technician locates the parent nest (often outside the house in a dead tree or stump) and satellite colonies using visual inspection and sometimes acoustic detection, then treats with targeted baits or perimeter insecticide. Addressing the moisture source is essential to prevent re-infestation.