Carpenter Bee: Xylocopa

Picture of carpenter bee eating nectar

Description Of Carpenter Bees

Carpenter bees are commonly mistaken for bumblebees, but they vary in terms of behavior, size, and appearance. Carpenter bees are solitary and dig galleries in wood, whereas bumblebees live in small underground colonies of up to 400 individuals.

Carpenter bees are much larger than bumblebees, ranging in length from 3/4 to 1 inch. Bumblebees have yellow and black hairy abdomens, while they have hairless shiny black abdomens. Carpenter bees and female bumblebees can sting. Carpenter bees can’t sting because they don’t have stingers, so they’re harmless. They become a problem when they burrow into the wood structure of homes. 1 Go To Source portal.ct.gov-‘Carpenter Bee

Carpenter Bee Species

Hundreds of species of carpenter bees exist worldwide, all belonging to the genus Xylocopa. Carpenter bees are well-known for burrowing into wooden structures such as houses, and different species use bamboo, plant stems, bricks, and lead-covered cables to construct nests. The most abundant carpenter bee species found in different parts of the United States are listed below.

  • Horsefly-like Carpenter Bee
  • Southern Carpenter Bee
  • Sonoria
  • Valley Carpenter Bee
  • California Carpenter Bee
  • Eastern Carpenter Bee

Carpenter Bee Behavior

Picture of a flying carpenter bee

Carpenter bees, unlike honeybees and bumblebees, do not live in colonies. Adults spend the winter on their own, often in brood tunnels that have already been built. Those who make it through the winter emerge and mate in the spring.

Female carpenter bees that have been fertilized bore into wood, excavating a tunnel to lay their eggs. The round entrance hole in the wood surface is about the diameter of your little finger. Below the opening, coarse sawdust may be present, and tunneling sounds may be heard within the wood. After a short distance of boring, the bee turns right and continues to tunnel parallel to the wood surface.

About five or six cells are built inside the tunnel to house individual eggs. The bee fills each cell with pollen (gathered from spring-flowering plants) and a single egg, then seals each chamber with regurgitated wood pulp, working backward. The pollen serves as a food source for the developing larvae during the hatching and maturation process, which takes several weeks. The new generation of adult bees emerges later in the summer and forages on flowers before hibernating in wood in the fall. 2 Go To Source entomology.ca.uky.edu-“Carpenter Bee”

Life Cycle Of Carpenter Bee

To build nests, female carpenter bees bore into sound wood, as well as decaying wood. Tunnels are typically 1/2 inch in diameter and 6 to 10 inches deep, divided into several chambers containing an egg and a supply of food, make up most nests (pollen). Carpenter bees may build their nests in old tunnels, which they occasionally enlarge; several bees may share a single entry hole that connects to multiple tunnels.

Tunnels can grow up to 10 feet in length in wood timbers over time. After the larval and pupal stages of the brood have completed their development, tunnels are vacated. It may take three months for an egg to mature into an adult.

Late in the summer, new adults emerge, feed on nectar and pollen, and overwinter in old tunnels that they have pollen-provisioned. In the spring, they emerge to mate, build and provision nests, and lay eggs. Each year, there is only one generation. 3 Go To Source ipm.ucanr.edu-“Carpenter Bees”

Habitat Of Carpenter Bee

Carpenter bees build their nests in dead trees, stumps, logs, and other dry coniferous woods. They nest by digging long tunnels up to 47 cm long into the wood. Cypress, pine, and juniper trees are familiar places to find nests. Carpenter bees prefer to build their nests in unpainted or barkless wood. They like to build their nests in areas with plenty of light. This species frequently lays its eggs in the same spot for several generations. 4 Go To Source animaldiversity.org -“Xylocopa virginica carpenter bee”

Carpenter Bee Diet

Photograph of flying carpenter bee

Adults feed on flower nectar, sometimes biting a hole in the base of the petals to “rob” the nectar without pollinating it. They do, however, pollinate a variety of flowers, including passionflowers (maypops).

The female fills her nest tunnels with nectar and pollen, then lays her eggs on top of it, which feeds the developing young. In the spring and summer, carpenter bees are busy preparing their nests. 5 Go To Source nature.mdc.mo.gov-“EASTERN CARPENTER BEE Xylocopa virginica”

Predators Of The Carpenter Bee

Carpenter bees are preyed upon by woodpeckers, shrikes, and bee-eaters, as well as some mammals such as ratels. Giant mantises and predatory flies, particularly large robber-flies of the Asilidae family, are other predators. The noise of the bee larvae attracts woodpeckers, who drill holes along the tunnels to feed on them. Aside from direct predators, parasitoidal bee flies lay eggs in the entrance to the bee’s nest, and fly maggots feed on the bee larvae.

Damage Caused By Carpenter Bees

Carpenter bees pierce wood with circular tunnels. You might be surprised to learn that a single carpenter bee can build a tunnel about 1 foot long. They usually take to the air and cling to a piece of wood. Then they dig a tunnel through the wood. They turn a corner and follow the grain of the board a short distance. The majority of the time, it’s a 90-degree turn. As they dig these tunnels, the wood begins to rot. This weakness can spread to other boards, causing the entire structure’s frame to warp. Walls can bulge, floors can sink, and ceilings can dip when this happens.

Carpenter bee damage frequently progresses to this stage. Unlike termites, which spend almost all of their time inside the wood they eat, carpenter bees do not mind being exposed to the air or sunlight. As a result, you’re more likely to notice holes in wood that carpenter bees have bored into. This occurs when the tunneling bee gets too close to the wood’s surface. Rooflines and eaves are familiar places to see this.

Carpenter Bee Removal & Damage Repair

A thorough inspection performed by an insect management professional is the first step in preventing and treating carpenter bees. During the inspection, a technician will look for the pest that is causing the problem as well as any damage.

The bee control plan is created after the inspection is completed. The most effective control method is to dust an insecticide into the bees’ drill holes and leave them exposed for a few days so that returning bees come into contact with the insecticide.

The drill holes will be sealed and repainted once the bees have died. Applying an aerosol spray to control free-flying carpenter bees can be useful at times. While only a temporary solution, applying a liquid insecticide to the wood surface takes less time than dusting drill holes. Painting any bare, exposed wood surfaces that are being attacked with exterior paint or a polyurethane finish is a non-insecticide control technique.

 

 

Sources:

  1. “Carpenter Bees.” CT.Gov – Connecticut’s Official State Website, portal.ct.gov/CAES/Fact-Sheets/Entomology/Carpenter-Bees. Accessed 16 Apr. 2021.
  2. Potter, Michael F. “Carpenter Bees | Entomology.” UK College Of Agriculture, Food and Environment, University of Kentucky, 7 Sept. 2018, entomology.ca.uky.edu/ef611.
  3. “Carpenter Bees Management Guidelines–UC IPM.” UC IPM, University Of California, ipm.ucanr.edu/PMG/PESTNOTES/pn7417.html. Accessed 16 Apr. 2021.
  4. Hauze, D. 2020. “Xylocopa virginica” (On-line), Animal Diversity Web. Accessed April 16, 2021 at https://animaldiversity.org/accounts/Xylocopa_virginica/
  5. “Eastern Carpenter Bee.” MDC Discover Nature, State Of Missouri, nature.mdc.mo.gov/discover-nature/field-guide/eastern-carpenter-bee. Accessed 16 Apr. 2021.