The carpenter ant (Camponotus spp.) hollows out wood to create nests called galleries. Though they do not eat the wood, the boring activity can lead to structural damage in wood components. The by-product of the boring is called frass and looks similar to sawdust or pencil shavings. Frass is the most common evidence of carpenter ant infestation.
Carpenter ants are similar in appearance to the common pavement ants, but can be distinguished by certain physical characteristics. The carpenter ant has a single pinched node between the abdomen and the thorax, while most ants have a dual node. In addition, the profile of the section from the abdomen to the head is almost perfectly rounded. Carpenter ants are especially common in the Northwest and the Pacific Northwest.
The most thorough and effective way to treat a carpenter ant infestation is to locate the nest (colony) or nests and directly apply an appropriate pesticide. This may involve drilling into wood member and using pressure injection. It may also include drilling into the wall voids and on top of window sills and applying a dust-like pesticide. Another strategy involves laying out poison baits for the worker ants to take back to the nest(s). To prevent infestation, barrier treatments and removal of conducive conditions is recommended.