Carpenter bees are often mistaken for thier cousin, the bumble bee, but there are some differences . It is so named because they excavate galleries in wood to create nest sites. They do not consume wood. Rather, Carpenter bees typically are just nuisance pests that cause cosmetic rather than structural damage to wood.

Nonetheless, considerable wood damage can result from many generations of carpenter bees enlarging existing galleries in wood. Large carpenter bees belong to the genus Xylocopa. Two native species, Xylocopa virginica and Xylocopa micans, occur in the eastern United States. There also are a number of native carpenter bees in the western United States. This fact sheet primarily pertains to X. virginica, which has the common name of carpenter bee.

Carpenter bees over winter as adults in wood within abandoned nest tunnels. They emerge in the spring, usually in April or May. After mating, the fertilized females excavate tunnels in wood and lay their eggs within a series of small cells. The cells are provisioned with a ball of pollen on which the larvae feed, emerging as adults in late summer. The entrance hole and tunnels are perfectly round and about the diameter of your finger. Coarse sawdust the color of fresh cut wood will often be present beneath the entry hole, and burrowing sounds may be heard from within the wood. Female carpenter bees may excavate new tunnels for egg-laying, or enlarge and reuse old ones. The extent of damage to wood which has been utilized for nesting year after year may be considerable.

Carpenter bee damage to wood initially is minor, and carpenter bees seldom cause consequential structural damage. However, their repeated colonization of the same wood can eventually cause considerable wood damage. Carpenter bees preferentially refurbish and enlarge an existing tunnel instead of boring a new one, and a gallery can extend for 10 feet if used by many carpenter bees over the years.

Carpenter bees sometimes construct new tunnels near old ones, with infestations persisting for several years. This complex system of tunnels can result in extensive damage to wood. Wood replacement is necessary when the strength of structural members, posts, poles, and other wood products is reduced due to carpenter bee damage.

Carpenter bees also may be indirectly responsible for unsightly wood damage when woodpeckers riddle the wood with holes searching for the developing carpenter bees to feed upon.

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