Of all the insects I receive calls about, carpenter bees are among the top five. Carpenter bees derive their name from their nesting habits, in fact their genus name of Xylocopa translates from ancient Greek to mean “wood-cutter.” A very fitting name for an insect with a preference for wood as their nesting sight. In the spring females will mate and begin looking for suitable locations to excavate a nest. Unpainted, untreated, weathered wood is her prime choice, and if the wood is cypress, cedar, redwood or pine all the better. These softer wood varieties make her life easier. She may also utilize nesting sights from previous seasons and just expand their size. Typically, their nesting behavior does not cause significant damage as the tunnels run along the surface of the wood, and not into the heart wood. However, the continuous use of nesting locations can cause problems. These nesting locations also attract an animal that can be a big issue for homeowners…. woodpeckers. These birds are attracted to the feeding and movements of the larva within the tunnels. They can hear them, and the temptation is more than they can bear, they will drill into the wood until they reach the tasty morsel inside. This can and does cause significant damage to homes, decks and other wood surfaces.
Believe it or not some people do not notice these large bees, but rather find suspicious looking piles of sawdust on the ground under the eaves of their home, or in their outbuildings. Glance up, and you will find the culprit leaving you these little piles of wood shaving. Eaves of homes, rafters, fascia boards, wood siding, decks, patio furniture and other weathered wood are all at risk of being used as nesting locations.
Males have yellow patches on their face that are visible at this range. Rest assured they cannot hurt you; they are just asking you to leave. Females typically stay busy boring into wood and laying eggs, they don’t have time to pay you a visit like the males do.
She will bore a short distance into the wood then veer right and continue tunneling parallel to the surface of the wood. She creates five chambers that she provisions with pollen, after laying an egg in each chamber she seals them up with pulp made from bits of wood and saliva. In a few weeks the adults emerge. Often these new adults will spend the winter in the brood chambers and emerge the following spring. These will be the adults that create the next generation. Occasionally other bees or wasps will be found emerging from these entrance holes. No need to worry, they are not compounding the problem created by the carpenter bees. These are opportunistic hunters looking for a cheap and easy meal in the form of leftover pollen.
Generally, the calls I receive are inquiries into how to control these bees or get rid of them entirely. While I can understand the concern, generally their feeding habits, while unsightly at times, are not damaging, certainly nothing like termites would do. These bees are known to pollinate many flowers and should be considered beneficial…although there are some sneaky individuals that have figured out a way to steal nectar without benefiting the plant at all. These thieves use their mouth to make a slit in the sides of flowers and enter through this opening, helping themselves to the tasty sweetness inside and leave without taking any of the necessary plant pollen to propagate the next generation of plants.
If you are determined they need to go, control can be challenging. There are homemade traps you can try. These traps are made from wood with a ½ inch hole drilled into each side and a plastic bottle suspended from the bottom. The bees investigate the opening and fall into the bottle. They are unable to climb out and die (Google carpenter bee trap). When enough bees have accumulated simply empty the bottle and reuse. Others I know have had good luck using a brown paper sack. Fill the sack with air, tie it off at the top and suspend it near the area where the bees are boring into the wood. This air-filled sack resembles a bald-faced hornet nest, and these large wasps are sworn enemies of the carpenter bee. This may discourage the bees from using this area. Any surface that is unpainted may be painted as a way of discouraging them as well. As a last resort you can try various insecticides. Some may need to be reapplied frequently as their residual effect does not last long. Always follow directions carefully.
If their footprint is small and damage is minimal living with these large, curious bees benefits many of the flowers and vegetables we grow through pollination. Tolerance is almost always the best policy.