Carpenter ants are large reddish black or black ants that can be up to1/2 inch long. You can find them entering and exiting holes in the trunks of trees. The holes they burrow in are smooth on the inside and piles of fibrous coarse sawdust like material collect on the ground beneath the holes. These insects burrow into moist decaying wood and make their nests. They take over dead stumps and trees, but also they may invade living trees. They prefer rotting wood so the living trees they colonize may have heart rot. They do not eat the wood, but however live off of other insects, pollen, seeds and honeydew. Carpenter ants endanger the trees and can eventually make the tree dangerous.