Carpenter bees (Xylocopa sp.) are very large, wood boring bees that become active in early spring. They range in size from ¾ of an inch (1.9 cm) to one inch (2.5 cm) long and are about ½ inch (1.3 cm) in diameter. Carpenter bees have a yellow thorax and a black, shiny abdomen. They are often confused with their close relative the bumble bee; however, bumble bees have a fuzzy rather than a smooth abdomen.

Carpenter bees can become a problem, as they like to nest in houses or other domestic structures made of wood. Very adept drillers, the female carpenter bees quickly bore holes in wood siding, eaves and decks to lay their eggs. Nest sites are marked by very noticeable sawdust accumulation below their holes. The holes may appear to be superficial at about one to two inches (2.5-5cm) deep, but from this point, female carpenter bees make a 90º turn and burrow downward up to four feet (1.2m).

Once the nest has been excavated, the female carpenter bee deposits her eggs and stuffs the hole with pollen for her offspring to eat when they hatch. Laying only one egg per nest, female carpenter bees may bore many different holes in close proximity to one another, which may exacerbate problems for homeowners.

Carpenter bees, unlike most bee species, only travel in mating pairs. While the female is drilling her nest, the male carpenter bee acts as a guard. Male carpenter bees hover around the potential nest site, buzzing loudly and aggressively chasing any insects or other animals that come near.

Due to their size, male carpenter bees may seem very threatening, but they are in fact quite harmless because they do not have a stinger. Female carpenter bees do have a stinger and the ability to sting, but they are by nature very docile. A female carpenter bee will only sting if she is handled or abused. Male carpenter bees attempt to scare people away, but when left alone they simply resume hovering around their nest. Carpenter bees are mostly concerned with predatory insects and usually ignore people and pets.

Carpenter bees are profuse pollinators and are therefore an important part of the ecosystem. Unless they are damaging one's home, they are not a threat to people. While carpenter bees prefer raw wood over painted or stained wood, painting or staining won't necessarily immune your home from attack. Commercial pesticides labeled for wasps and hornets also work to kill carpenter bees when necessary. Perhaps the best method for prevention is treating the problem at its source, the nest, if possible.