Carpenter Bees

General Information

The carpenter bee is one of the largest bees found in the United States. Though several different types of carpenter bees live throughout the U.S., Xylocopa virginica is the most prevalent species in eastern regions of the country. Like other bee species that inhabit the area, carpenter bees facilitate the growth of vegetation by pollinating flowers and other plants. Carpenter bees are generalist pollinators that pollinate many different kinds of plants , but the beneficial insects often serve as particularly capable pollinators of vegetable crops like eggplant and tomatoes. As their common name suggests, carpenter bees are also capable of boring into wood and causing aesthetic, and sometimes even structural, damage to homes.

Appearance & Identification

What do carpenter bees look like?
Carpenter bees resemble the widely recognizable bumble bee in appearance. Both types of bees grow to as long as an inch in size and have round, black bodies covered in stripes of yellowish hair. However, while bumble bees are hairy over the entire body, the abdomen of a typical carpenter bee remains hairless and has a glossy black sheen. Carpenter bees also exhibit slight physical differences between males and females within the species. The head and face of adult male specimens feature white markings, while females have an entirely black head.

Habits/Habitat

Unlike the social bee species (bumble bees and honey bees), carpenter bees are solitary and do not establish large colonies nor live according to a caste system. The insects live up to their name by excavating galleries from trees and other wood structures to carve out sites for nesting and overwintering. Taking advantage of their powerful jaws, or mandibles, female carpenter bees construct the galleries by selecting a suitable piece of wood, creating a distinctively round entrance hole, and drilling through the material to produce a tunnel. Carpenter bees then use chewed wood to create walls and partition the gallery into individual sections, each of which eventually houses an individual egg.

The eastern carpenter bee generally prefers to make galleries out of softer woods, such as cedar, cypress, fir, and pine. While females construct the galleries and lay the eggs, male carpenter bees are often seen hovering outside the nest site and chasing trespassers away. Though males cannot sting, they defend the nest with vigor and frequently fly in the personal space of humans, commonly inciting undue panic. Only female carpenter bees have functional stingers, which the they rarely use.

Diet

What do carpenter bees eat?
Adult carpenter bees do not actually ingest the wood they excavate and instead feed on the nectar of flowers. Due to their large size relative to other bees, carpenter bees cannot fit into the openings of certain flowers and instead use their strong jaws to make a slit and access the nectar at other points on the plant. The excavating insects also combine pollen with regurgitated nectar to create a food source for newly hatched eggs and subsequent larvae to feed on through all the stages of development.

Reproduction

After mating with young males in the spring, female carpenter bees construct wood galleries and lay eggs within the resulting tunnel. Carpenter bees lay a single egg on top of the mixture of nectar and pollen in each section of the partitioned gallery. Larvae hatch from the eggs and begin consuming the food source to gain the nourishment necessary for complete development. Like other bee species, carpenter bees develop into pupae after the larval stage and eventually become fully grown adults roughly seven weeks after hatching. Newly matured carpenter bees emerge from the excavated gallery during late summer to feed and return to the tunnel to overwinter through the winter.

Problems Caused by Carpenter Bees

While carpenter bees rarely sting or live in groups large enough to pose a dangerous threat to humans, the insects can cause problems by excavating galleries out of wood. Although trees often make adequate nesting sites, carpenter bees frequently lay eggs and overwinter in the wood of decks, outdoor furniture, and houses. The excavating insects mainly create cosmetic damage by chewing entrance holes into the wood and staining the area below the entryway with excrement and pollen. However, carpenter bees can also cause structural damage when multiple generations of the insects inhabit and enlarge the same wood gallery over an extended period of time.

Signs of Infestation

The entrance hole is a telltale sign of carpenter bee activity. Entrance holes are roughly a half-inch in diameter and almost perfectly round. Carpenter bees may also leave yellowish or brownish stains of pollen and excrement in the vicinity of the entrance hole. Males often hover, an action typically not performed by other bee species. In fact, if a large fuzzy bee is seen hovering under the eaves of a house, chances are the insect in question is a carpenter bee.

Prevention

One of the easiest ways to prevent carpenter bees from nesting is to reduce the attractiveness of the wood. As the flying insects generally prefer to excavate bare and untreated wood, home owners should consider painting or staining exposed wood structures around the outside of the house. Homeowners should also keep in mind that carpenter bees most often select softer woods for nesting and overwintering, making hardwoods perhaps a better choice for completing any kind of construction or project. Carpenter bees like to reuse previously excavated wood galleries, as well. Area residents should therefore locate and seal all entrance holes while making sure not to trap any carpenter bees inside, as the excavating insects will simply chew new tunnels and escape. For the best and safest results in managing and preventing carpenter bees, contact a professional pest control service.


The carpenter bees are the most common wood boring bees that people see. The carpenter bees are in the family Anthophoridae. They attack wood siding, eaves, windowsills, decks and railings, and even patio furniture. Some of the leafcutting bees in the family Megachilidae have been known to attack siding on homes and barns.

The wood boring bees make a half an inch hole in the wood. When the hole is an inch deep, the bee turns the tunnel to follow the grain of the wood. The tunnels are normally 5″ or 6″ deep. Sometimes several female bees work together to extend old tunnels from previous years. Scientists have found wood-boring bee tunnels that extended more than 10′ into the wood.

The wood boring bees can deface a home with their tunneling. Many times several bees make their tunnels in the same area. If they are allowed to work undisturbed, after a time they can cause structural damage.

The female bee places a small supply of pollen and nectar at the end of the tunnel. She places an egg next to the food and seals the chamber. She makes a second chamber beside the first. By the time she has finished, she will have built a series of egg chambers. When the last chamber I built, the female bee leaves.

When the eggs hatch, the larvae will eat the food that was provided. The larvae develop inside the chambers. When they have matured into adult bees, they break the partition that sealed the chamber and come out. They find mates and start the cycle again.

Insecticide can control these wood-boring bees. Dust or wettable powder insecticides are most effective because they do not soak into the wood. Insecticide must be injected into each tunnel. The challenge is to make the application without spilling any insecticide on the surface. There is also a risk of insecticide splashing back into the face of the person making the application. Many people prefer to have a pest control professional make the treatments.

After the treatment, the homeowner should wait a few days before sealing the holes. The adult bees can be exposed to the insecticide by crawling in and out of the tunnels. The new bees will be exposed when they hatch.

Caulking or wood dowels are good for plugging the holes. It is not clear whether painting wood actually prevents wood boring bees from attacking. Scientists agree that wood-boring bees are less likely to attack painted wood than bare wood.