These are very small ants, varying in colour from pale yellow to brown, with a darker abdomen. The petiole, the part that gives ants their slender waists, has two small nodes.
Adults in the colony belong to different castes. Workers are sterile females from 1.5 to 2.5 mm long. Queens, larger and darker, are from 3.5 to 5 mm. A single colony may have several queens. Males are about 2.8 mm long. Queens and adult males have wings when they emerge.
Carpenter ants are black, tinged with red or brown depending on the species. Males are 9 to 10 mm long, with small heads and two pairs of wings. Females are either queens or workers. Future queens have wings.
The queen is usually much larger than the workers, with a well-developed abdomen.
Workers are from 6 to 13 mm long. Their appearance differs depending on their role: nurses, scouts, soldiers, etc.