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A source for information on bees
Carpenter Bee Family Anthophoridae



The species of most importance are about 1-inch long and have a robust, bee-like shape.


Like bumblebees, carpenter bees are black with some yellow. One carpenter bee species in the southwest, the valley carpenter bee, has a metallic-black colored female and a tan colored male.


Carpenter bees chew out tunnels in wood in which to lay their eggs and provide a protected site for their larvae to develop. The female bee selects a suitable log or piece of wood and chews a round, 1/2-inch diameter tunnel into the wood. About one-inch deep, she turns at a right angle and chews a tunnel (nest gallery) about 12 inches in length. The bits of wood she chews off are deposited outside the nest and end up on the ground below. These bits of wood, called frass, often are streaked yellow from pollen on the female s legs. An egg will be deposited at the end of the nest gallery; the female will then pack the gallery about an inch deep with pollen. This process is repeated until the entire gallery has been filled. The male carpenter bee guards the outside of the nest and tries to chase away potential predators. He does not have a stinger, but still causes concern with his aggressive buzzing if people venture near the nest site.

Carpenter bees are solitary insects that differ from other bees as they do not form colonies. Adults emerge in spring to mate. Carpenter bees are so named because they nest in excavated galleries in wood; however, they do not eat it, preferring to feed on pollen and nectar. They are actually important pollinators of flowers and trees. They are generally cause cosmetic rather than structural harm to wood, but numerous generations can cause considerable damage to existing galleries over time.

Using her strong jaws, the female carpenter bee will bore a clean cut, round entrance hole on the lateral surface of wood that will evolve into a sort of gallery over time. It is a time and energy consuming process and they prefer to enlarge an old nest rather than excavate a new one. The female will work into wood perpendicular to the grain for 1-2 inches and then make a ninety-degree turn and excavate along the wood grain for 4-6 inches to create a gallery or tunnel.

Carpenter bees are solitary insects that differ from other bees as they do not form colonies. The male does not live long, so after mating in the spring, the female alone forms 6-10 “brood cells” inside. They consist of a formed ball of pollen and regurgitated pollen at the far end of the gallery. She lays an egg on this mass, which is walled off with a plug of chewed wood pulp, and dies soon after this labor. The larvae feed on the mass until adulthood, which usually takes around seven weeks.

The new adults stay in the gallery for several weeks and then chew through the cell walls and venture out in late August. They collect and store more pollen and travel back and stay in the gallery through winter, emerging the following spring to repeat the cycle. Male Carpenter bees are considered a nuisance pest but are harmless to humans as they lack a stinger. Females do have a stinger, but are typically docile and tend to sting only when handled.

In nature, logs and dead trees and limbs are the targets for carpenter bees as nest sites. On homes, bare wood decks, fences, and window sills is usually attacked. Painted wood, however, is subject to attack although bare wood is preferred.

Carpenter bees nest in a wide range of softwoods and hardwoods, particularly if it they are weathered. It is easier for them to tunnel through woods that are soft and have a straight grain. They typically prefer softwoods such as pine, fir, cedar, cypress, oak, and redwood.

Carpenter bees also attack structural woods and other wood products, such as fence posts, utility poles, arbors, firewood, and wooden lawn furniture. In buildings, they nest in bare wood near roof eaves and gables, fascia boards, porch ceilings, decks, railings, siding, shingles, shutters, and other weathered wood. They tend to avoid wood that is well-painted or covered with bark.

Carpenter bees usually do not make their entrance hole in an exposed area. The inner lip of fascia boards is a common site of attack, as well as nail holes, exposed saw cuts, or other weakened areas.

Economic/Health Concerns:
Though carpenter bees seldom cause significant structural harm, their repeated colonization of the same wood and the use of the same colony over many generations can eventually cause considerable wood damage.

Carpenter bees sometimes build new tunnels near old ones, which they continuously labor to enlarge and refurbish. A gallery can extend for 10 feet or more over time. Replacement is necessary when the strength of structural beams, posts, poles, and other wood products is reduced from bee damage.

They also leave unsightly damage by depositing yellowish to brownish streaks of excrement and pollen on surfaces below entry holes.

keep all exposed wood surfaces well painted with polyurethane or oil-base paint to discourage Carpenter bees from excavating since they can easily attack exposed wood. Seal existing holes with caulking, wood putty, or a wooden dowel affixed with wood glue. If possible, fill the entire gallery with sealant. Carpenter bees will not chew their way out of a sealed gallery due to behavioral constraints.

In new nests, larvae and pupae can be killed by inserting a long wire into the entrance hole and probing into the gallery as far as possible. Wood stains will not prevent damage, so consider using aluminum, asphalt, vinyl siding and similar non-wood materials that Carpenter bees avoid.

Painting bare wood that is being attacked by carpenter bees can deter some bees; however, it does not offer the best solution.

  • If the wood targeted by bees is treated with a residual pest control product, carpenter bees may be repelled or killed by the treatment.
  • Once holes have been started, the nest galleries may be treated.
  • The holes can be plugged several weeks later when it is positive that the bees have been killed.
"Riley Pest Management is a small company with a big heart that will go the extra mile to take care of an issue for you no matter when it happens. They have proven to be a very good friend to non-profits."

-- Duggan Cooley, former CEO- RCS

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