Carpenter Bees closely resemble bumblebees, but their abdomens are black and shiny, lacking the yellow stripe found on a bumblebee’s abdomen. They are also about the size of a bumblebee, 1/2 to 1 inch. They excavate their homes, called galleries, in wood, where they lay their eggs. The entrance hole is only about ½ inch in diameter, but the gallery can be much larger. Insects that hover around the eaves of your house are usually carpenter bees.
Their common name is because nearly all species build their nests in burrows in dead wood, bamboo, or structural timbers which nest in the ground. They are traditionally considered solitary, though some species have simple social nests in which mothers and daughters may live together.
Carpenter bees make nests by tunneling into wood, vibrating their bodies as they use their front claws against the wood they excavate, and each nest has a single entrance which may have many adjacent tunnels. The entrance is often a perfectly circular hole on the underside of a beam, bench, tree limb or wood dwelling.
Carpenter bees do not eat the wood they excavate. They discard the bits of wood, or reuse small particles to build partitions They use wood bits to form partitions between the cells in the nest. Since the tunnels are near the surface, structural damage is generally minor or nonexistent.
Solitary bees tend to be social and often several nests are near each other. In solitary nesting, the founding bee forages, builds cells, lays the eggs, and guards. Normally only one generation lives in the nest.
Male carpenter bees are harmless, since they do not have a stinger, but they can be a nuisance. The females are capable of stinging, but they are docile and rarely sting unless caught in the hand or otherwise directly provoked.