Carpenter ants are among the largest ants in the United States, ranging from 3.4 to 13 mm long. The most common color is black, but some species have reddish or yellowish coloration. Workers have large mandibles. Carpenter ants reside both outdoors and indoors in moist, decaying or hollow wood. They cut galleries into the wood grain to form their nests and provide passageways for movement from section to section of the nest. This activity produces wood shavings mixed with parts of dead ants which provides clues to nesting locations.