Carpenter Ants

Carpenter Ants


carpenter ants


Carpenter ants are the #1 wood-destroying pest in the Pacific Northwest. Left unchecked, carpenter ant colonies can cause significant damage to sound wood, possibly compromising the structural integrity of a building.

Carpenter ants are fairly easy for an untrained person to identify with the naked eye. The easiest way is by size and color. The most common local species (Camponotus modoc), is “a big black ant” by anyone’s definition. Although workers vary in size somewhat within a colony, even the smaller workers are larger than most other ants one is likely to have encountered. Insects have three body segments, and in C. modoc the head, thorax, and abdomen are all black – the abdomen may have some silvery bands. The legs are reddish. The second most common species (Camponotus vicinus) has a black head and abdomen; the thorax is lighter, usually reddish.


Carpenter Ant Colony


Carpenter Ants (7)

Before attempting to deal with carpenter ants, it’s important to know that there are two types of colonies – primary colonies and secondary colonies. A primary colony contains the queen, eggs, and early stages in their larval development. It is nearly always located outside the structure, and most likely in the ground, since the queen, eggs, and early larvae need to be kept wet. Late-stage larvae and pupae, however, must be kept in a drier place.

Satellite colonies are established by worker ants. They find an appropriate place above grade (a hollow tree, a post – or a house), prepare the area (possibly by digging tunnels and chambers in good wood), and then carry many larvae into the area. The larvae then pupate, and new workers emerge.

A carpenter ant colony in a structure, in nearly all cases, will be a satellite colony. Therefore, after it has been eliminated, it is essential to keep up a barrier treatment with a proper insecticide, lest the primary colonies outside simply restock the area and therefore allow the wood damage to continue. Finding primary colonies can be very difficult, since carpenter ants will trail hundreds of feet. And even if the primary colony is found and successfully killed, there is probably another primary colony within range of the building.

How to Get Rid of Carpenter Ants


Carpenter Ants Inside the structure of the roof coming out

Carpenter ants may be eliminated by a wide range of products and methods, selection of which depends on the colony location, time of year, and many other factors. In cases where the carpenter ants being sighted in a structure are coming from a satellite colony (and not just foraging in from a primary colony), it is best to contact an experienced professional exterminator.


Queen lays 15 to 20 eggs the first year and up to 30 eggs the second year. Eggs complete their life cycle in about 60 days. Worker ants can live up to seven years, while a queen may live up to 25 years.

Tips for Prevention

• Remove any piles of debris, wood, and junk from around your home.

• Keep trees, shrubs, and plants trimmed and away from your home.

• Caulk cracks and crevices around foundations that provide entry from outside.

• Provide a dry, vegetation-free border, such as gravel or stones, around the perimeter of house foundations to discourage nest building. Wood chip mulches and landscape plants provide a good nesting environment.

• Keep food put away and don’t leave dirty dishes out.