Carpenter Ants

How to identify carpenter ants

Among the largest ants you'll see indoors, ¼–½ inch long and usually black (sometimes dark red-and-black). Unlike termites, they don't eat wood — they hollow it out to nest, leaving behind piles of sawdust-like shavings called frass.

Why it matters

Carpenter ants nest in wood that's been softened by moisture — around leaky roofs, window frames, decks, and crawlspaces. Left alone, a colony expands its galleries over years and can cause real structural damage.

Seeing large black ants indoors, especially in winter or spring, often means a nest is inside the structure rather than outside. Spraying the trail you see rarely reaches the parent nest, so the problem keeps coming back until the colony itself is treated.