Carpenter Ants
Carpenter ants are an important part of our ecosystem. They excavate and break down wood. Their nests are very common inside trees, especially older trees that are hollow or have a significant amount of deadwood. The nests are usually found in rotted, decayed wood; some nests may extend into sound heartwood. They do not eat wood, but tunnel into the wood to make a nest. If you suspect you have carpenter ants, look for piles of wood shavings outside a hole or opening. The wood shavings will be coarse and there will be insect parts mixed among them.
Damage
Carpenter ants are not directly harmful to the tree. Control is not essential for the tree's health. The ants are only taking advantage of a pre-existing situation of soft, weak wood in which they are able to establish their colony.
Control
Control of carpenter ants inside trees is difficult, but can be done as a way to reduce invasion of ants into adjacent structures. (It is possible for ant colonies located inside trees to form satellite colonies inside a nearby home wall.)
If you are worried about carpenter ants becoming a problem, visit your local garden center to pick up something to treat them. We have found that Seven, a product available at most garden centers, has been known to do the trick in most cases.