Carpenter Ant Infestation

Signs of a Carpenter Ant Problem

The first clue is usually large ants crossing a kitchen counter or bathroom floor, often after dark. Seeing them indoors does not prove they are nesting inside. Workers often live in a tree, stump or landscape timber in the yard and walk into the house through gaps along the foundation, around utility lines or along branches that touch the roof. They come in looking for water, sweets, grease and protein, including dead insects. Other signs include small piles of coarse shavings mixed with insect parts below openings in wood.

Tracking Down Carpenter Ant Nests

Because the ants are busiest at night, a flashlight check an hour or two after dark is the easiest way to follow them. Watch where the trails lead, both inside and along the outside walls. Also look at decks, fences, firewood stacks and trees close to the house. A dim light or a red lens disturbs them less. Winged ants collecting at an indoor window, especially in the warmer months, suggest a mature colony is nesting somewhere inside the structure.

Carpenter ant colonies often have more than one nest. A main nest holds the queen and the youngest brood, while satellite nests in other spots hold workers and older brood. A satellite nest can sit inside a home while the main nest is outdoors, and workers travel back and forth along regular trails. Treating only the ants you can see tends to fail, because the hidden nests keep sending out new workers.

Inside a house, look where wood has stayed damp or where there is a hollow space: around leaking windows and doors, under tubs and sinks, in rotted roof eaves, in porch columns and in wall voids behind siding. Foam insulation and hollow-core doors are also common nesting spots.