There are several species of carpenter bees that are fairly small, but the common species that may invade structural wood are some of the largest bees in North America, with some of the largest over one inch long.
Carpenter bees are normally shiny metallic blue-green to black, although the male may be light tan.
Carpenter bees are solitary bees that get their name from their habit of boring chambers in solid wood in order to create living quarters for their larvae. The wood is not eaten, but instead is reduced to sawdust, called frass, and ejected from the tunnels. The female carpenter bee does the excavating, and several females may work in the same section of wood and use the same entrance hole, but they create separate galleries for housing their larvae. The galleries may be used repeatedly, with each new female lengthening the tunnel, which often can reach over ten feet in length.
Carpenter bees dine on pollen and nectar.
Males and females spend the winter in old galleries and emerge in the spring to mate. The female creates an average of six or seven cells; each separated by a plug, and places an egg and a food supply of pollen and nectar in each cell. Once this is completed she never returns to care for the larvae. The male carpenter bee guards the outside of the nest and attempts to chase away predators. The male does not have a stinger, but can cause concern with his hostile buzzing.
Damage from carpenter bees is hidden within wood, often with only the round entrance hole visible. Males can be very aggressive, but do not have a stinger. Females do have a stinger and will sting if they become agitated. Carpenter bees often use the same tunnels and galleries year after year and wood damage can become extensive.