Carpenter ants are social insects, living in colonies with a rigid caste system consisting of a queen, workers and reproductives (swarmers), i.e. sexually mature males and females that swarm and set up new colonies.
Worker ants can live about four to seven years and the queen can live for as long as 15 years, however colonies have been known to last for 30 or even 40 years. When the queen dies, specially fed workers take over the egg-laying function.
There is a great difference between carpenter ants and termites: carpenter ants do not eat wood, they just excavate it to build a nest. This nest consists of irregularly shaped galleries, generally following the grain. The small fragments of shredded wood generated through excavation are removed from the galleries and deposited on the outside, so the galleries do not have the earthy appearance of the termite ones. Instead, carpenter ant galleries have a rather polished or sandpapered appearance.
Carpenter ant colonies can be located on the ground in a decaying log or tree trunk, as well as in the roof framing of a house. In addition, the ants also nest high in trees and they are able to fly from there to set up new colonies in a house. They can build their nests in a number of locations, but they prefer wood that is moist or softened by decay. Still, they can also build nests in wood that is perfectly dry and sound.
During a carpenter ants inspection, look particularly at sections of wood that have started to decay as a result of a moisture condition, either past or current. Although the source of the moisture might have been eliminated, ant colonies might have been established already.
Typical Locations to Inspect for Carpenter Ants
Portions of the wood framing, siding or trim that are in contact with the ground are especially vulnerable to a carpenter ant infestation. Also, examine any wood that has been dampened by the overflow from defective roof gutters, the area around a damaged section of siding or flashing, check the base of hollow porch posts and columns, as well as any areas with large open joints (sometimes around exterior windows and doors). These areas should be probed with an ice pick or a screwdriver, and if the wood yields, breaks or cracks and ants are crawling out, it is likely you have located a nest.
However, a carpenter ant nest is usually rather difficult to locate, because it is often established in inaccessible locations such as inside the wall or roof assembly. Unexplained piles of sawdust are a good indication of the existence of a carpenter and colony, though many people mistake such piles of sawdust for a sign of termite infestation. Keep in mind that subterranean termites completely devour the wood they are attacking, leaving absolutely no trace of wood particles. Dry-wood termites eat the wood completely as well, but they also drop tiny, well-formed seed-like pellets. Unless you look very closely, these pellets might be mistaken for irregularly shaped particles of sawdust.
If a house is infested with carpenter ants, it is very unlikely the occupants are not aware of the condition. Numerous worker ants will be walking across rooms, feeding on sweets, crumbs and other foods normally found or spilled on a kitchen floor or counter. Carpenter ants are very easy to recognize, as they are among the largest ants in the U.S. Worker ants vary in size between ¼ to ½-inch long, and they are black with a reddish brown midsection.
The first sign of infestation is generally the presence of ants in the house, however that does not mean the nest is actually inside the house. It might as well be outdoors and the ants may have entered the house foraging for food. A carpenter ants infestation can be controlled only by destroying the nest, be it directly or indirectly. If the nest is found, it can be treated directly with insecticide, but if not, dusts or sprays can be used where the ants are commonly seen. This might not eliminate the infestation, but it will reduce it significantly and allow you to somewhat control it until you find the nest.