Carpenter bees are a common sight, often recognized for their distinctive buzzing around wooden structures. Unlike social bees that live in colonies, carpenter bees are solitary, with each female independently creating a nest to raise her young. Understanding their reproductive habits, particularly when and where they lay eggs, helps clarify their presence and activities around homes and other wooden areas.
The Primary Egg-Laying Season
Carpenter bees begin their egg-laying activities in the spring. After overwintering in wooden tunnels, adult males and females emerge as temperatures rise, usually in April or May, to mate. Females then seek out suitable wood to excavate new nests or expand existing ones for egg deposition.
Egg-laying occurs from late spring through early summer. While most regions experience one generation per year, some southern United States areas may see a second, smaller generation emerge in late summer or early fall. The female focuses on nest construction and provisioning during this period.
Nesting Habits and Egg Chambers
Female carpenter bees create their nests by boring into wood. They prefer unpainted, weathered wood, including softwoods like cedar, cypress, pine, and redwood. The bee drills a circular entrance hole, about half an inch in diameter, perpendicular to the wood surface. After boring a short distance, one to two inches, the female turns at a right angle and tunnels along the grain of the wood.
These tunnels, known as galleries, can extend for several inches, with some reaching lengths of up to ten feet if reused and expanded over multiple years. Within these galleries, the female constructs individual chambers for her eggs. She provisions each cell with a mixture of pollen and regurgitated nectar, often called “bee bread,” which serves as food for the developing larva. A single egg is laid on this food mass, and then the chamber is sealed with a plug made of chewed wood pulp. Females lay between six to eight eggs in a single tunnel.
The Carpenter Bee Life Cycle
The carpenter bee undergoes a complete metamorphosis, progressing through egg, larva, pupa, and adult stages. After the female lays an egg in its provisioned cell, the egg hatches within two days. The larva then emerges and feeds on the bee bread, growing and developing over fifteen days.
Following the larval stage, the bee enters a prepupal stage for a few days before transforming into a pupa, a transitional phase lasting fifteen days. The total development from egg to adult takes seven weeks. New adult carpenter bees emerge from their nests in late summer, in August or September. These new adults forage for food before returning to the tunnels to overwinter, emerging the following spring to mate and continue the cycle.