The carpenter bee is a large, robust bee that bores tunnels into the untreated wood of structures. Generally black in color and 1/4 to 1 inch in length, these bees are often mistaken for bumble bees. Carpenter bees resemble bumble bees, but are solitary and do not build hives. The upper surface of their abdomen is bare and shiny black, while bumble bees have a hairy abdomen with at least some yellow markings. This type of stinging bee gets its name from its habit of boring into wood like a carpenter
The female carpenter bee begins her nest by drilling a perfectly round entrance hole (about 1/2 inch diameter) into wood. When the tunnel is about 1 inch deep, the bee turns at right angles and tunnels with the grain of the wood. Bees prefer to attack soft unfinished wood that is greater than two inches thick.
Carpenter bees hibernate in vacant nest tunnels during the winter. As the weather warms in spring, adult bees emerge and mate. Males die after mating, while females construct “brood chambers.” Females place a ball of food made of pollen and nectar into each chamber. She then lays an egg and seals the chamber shut. Eggs hatch within a few days, and 5 to 7 weeks later, the young bees reach adulthood. Carpenter bees typically live for about one year.
Because they look like bumbles bees, which do sting, carpenter bees evoke a great deal of concern. Males can be aggressive, but are harmless and cannot sting as they lack a stinger. Female carpenter bees do possess a stinger but seldom use it unless they are handled or provoked.
Carpenter bees can be a real nuisance to homeowners because they tunnel into decks, porches and other wood structures. These bees will readily return to the same wood or location where they were born. Old nests are used year after year and offspring will often times construct nests alongside old nests. For this reason, a single nest one year will become two or three the following year. If carpenter bees are allowed to tunnel in the same structure year after year, the cumulative damage can be significant.
Prevention is the main approach to managing carpenter bees:
1. Varnish or paint exterior wood surfaces to make them less attractive to bees. A fresh coat of paint is unattractive to a carpenter bee.
2. Fill unoccupied holes with steel wool and caulk to prevent their reuse. Wait until after bees have emerged before filling the tunnels.
3. Once filled, paint or varnish the repaired surfaces. Protect rough areas, such as ends of timbers, with wire screening or metal flashing.
It is rare for carpenter bees to cause extensive structural damage, but it can happen with a huge infestation that is not controlled early. In the case of an unmanageable carpenter bee problem, contact a professional.