Carpenter bees are large insects, often mistaken for bumblebees due to their similar size and fuzzy thoraxes. They typically measure between 0.75 to 1 inch long. Unlike bumblebees, carpenter bees generally have a smooth, shiny black abdomen, while bumblebees have hairy abdomens with yellow markings. These bees get their name from their nesting habits, which involve excavating tunnels in wood.
Do Carpenter Bees Build Hives?
Carpenter bees do not build communal hives like social bees such as honeybees or bumblebees. They are solitary insects; each female constructs and manages her own nest. While several carpenter bees might nest in the same piece of wood, each bee works independently, creating its own gallery for offspring. This contrasts with social bees, which live in organized colonies with a queen, workers, and drones. Bumblebees, for instance, typically build their colonies underground in abandoned rodent holes or similar cavities, rather than in wood.
How Carpenter Bees Create Their Nests
Female carpenter bees create their nests by boring into wood. They use their strong mandibles to excavate perfectly circular entrance holes, typically about 0.5 inches in diameter. After boring a short distance, usually 1 to 2 inches straight into the wood, the bee turns at a right angle and tunnels parallel to the wood grain. These tunnels, known as galleries, can extend for 6 to 12 inches.
Within these galleries, the female bee creates individual cells, often five or six, in which she lays a single egg. Each cell is provisioned with a mixture of pollen and nectar, sometimes called “bee bread,” to nourish the developing larvae. She then seals each cell with a partition made of chewed wood pulp. Carpenter bees prefer softwoods like cedar, redwood, cypress, pine, and fir, and they tend to select untreated or weathered wood for nesting.
Significance of Carpenter Bee Nesting Behavior
The nesting habits of carpenter bees have practical implications, especially for homeowners. Their tunneling can cause damage to wooden structures over time, including decks, eaves, fascia boards, and railings. While initial damage from a single bee is usually minor and cosmetic, repeated use and expansion of galleries by multiple generations can lead to more extensive structural weakening. Unlike termites, carpenter bees do not eat wood; they simply excavate it for nesting, discarding the wood shavings.
Evidence of carpenter bee activity includes the presence of perfectly circular entry holes and piles of coarse sawdust beneath the holes. You might also hear buzzing or scraping sounds from within the wood. Male carpenter bees are often seen hovering aggressively near nesting sites to defend the territory, but they are harmless as they lack stingers. Female carpenter bees possess stingers but are generally docile and will only sting if directly provoked or handled.