Last weekend I was delighted by a remarkable display of aerial daring-do while sitting at a picnic table at my brother’s home. Some of his deck is constructed of untreated lumber. Untreated wood provides perfect nesting sites for one of our most entertaining home invaders - carpenter bees. These crazed bumble-like bees hovered near my table, eyeballed me with malice, dive-bombed when I moved about, and engaged each other in serious aerial combat. Carpenter bees are very common and apparent around homes in spring when they construct nests in wooden structures such as decks, siding, benches, picnic tables, and fascia boards.
Males aggressively patrol and defend sites where females construct nests. The she bees cut nearly perfectly round holes about 1/2 inch in diameter in untreated wood. After entering the wood, the carpenter bee makes a 90 degree turn and constructs a gallery parallel to the surface of the board that may be more than a foot long. Galleries may be used year after year and reach several feet in length. After constructing the gallery, the carpenter bee makes individual cells and provisions them with pollen and nectar. She lays a single egg inside each cell. Eggs hatch and larvae consume the pollen cake throughout the summer. Larvae complete development and form pupae by autumn. Males and females emerge before winter and use the galleries as snug retreats during the cold months. They reappear in the following spring when blossoms return.
Carpenter bees are important pollinators of many native trees, shrubs, and herbaceous plants. They also help pollinate crops such as eggplants and peppers. While male carpenter bees are quite aggressive and appear menacing with their aerial antics, they lack a stinger and are harmless. Female carpenter bees have a stinger, but are very docile and unlikely to use their stinger unless severely provoked. Males can be distinguished from females by their whitish or yellow face. The female’s face is entirely black. Carpenter bees differ from their look-alike relatives the bumblebees by the lack of hair on their abdomen: furry, yellow rear end – bumble bee; shiny, black rear end – carpenter bee.
Bumblebees are social bees. They live in a colony with a queen and workers that care for young. Carpenter bees are solitary. Each female produces her own brood and, rather then tending the young, she provisions the gallery and departs. However, when a suitable nesting site is found like my brother’s deck, carpenter bees can be counted on to return year after year. One way to reduce damage caused by carpenter bees is to use pressure treated lumber when possible. For applications where pressure treated lumber is not appropriate such as siding, doors, sills, soffits, and fascia, keep wood painted or treated with preservatives and in good repair. Painted wood is less attractive to carpenter bees. Woodpeckers may be attracted to the activities and carpenter bees and, as they search for larvae inside the boards, significant collateral damage may result, but the entertainment value is hard to beat.
Thanks to my brother Gordon for sharing his carpenter bees. For more information on carpenter bees, please visit the following web sites.