This weekend while dining outdoors a pair of crazed bumble-like bees hovered near my table, eyeballed me with malice, and engaged in aerial combat. Closer inspection revealed not the industrious bumblebee but a lesser known aviator, the carpenter bee, Xylocopa virginica. Carpenter bees are commonly found around wooden structures such as decks, siding, benches, and picnic tables during April and May. Males of these large yellow and black bees aggressively patrol sites where females cut nearly perfectly cylindrical holes in wooden structures to create nests for their young. Using powerful jaws the female carpenter bee excavates a gallery ½ inch in diameter and up to a foot long within the wood. These tunnels may be used year after year and ultimately reach several feet in length. After constructing the gallery, the carpenter bee creates individual cells and provisions them with pollen and nectar. She then lays a single egg inside each cell. Eggs hatch and larvae consume the larder during the course of the summer. Larvae pupate and complete development to adulthood by autumn. Males and females may use the galleries as commodious retreats to spend the winter with a scheduled appearance in the following spring.

While the male carpenter bees are quite aggressive and appear menacing with their aerial antics, they lack a stinger and are harmless. Female carpenters have a stinger but are very docile and are unlikely to use their stinger unless severely provoked. Both males and females feed on nectar and pollen. Males can be distinguished from females by their whitish or yellow face. The she bee has an entirely black face. 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.

A good way to avoid damage to wooden structures 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 and in good repair. Painted wood is less attractive to carpenter bees. If you fear that carpenter bees are damaging your home, then pesticides may be used to curtail their tunneling. You will also see carpenter bees visiting flowers to gather provisions for their young.

References

For more information on carpenter bees visit:

http://www.hgic.umd.edu/pubs/online/carpenter_bees.pdf