These bees are generally non-aggressive, friendly, and even curious. Only the female possesses a stinger but doesn't use it unless threatened.
Botanically, carpenter bees are classified in the genus Xylocopa, which includes approximately 500 species in 31 subgenera. Their common name, "carpenter bee", derives from their nesting behavior. Almost all species burrow into hard plant material like wood or bamboo. The main exceptions are species in the subgenus Proxylocopa which dig their nesting tunnels in soil.
People are frequently alarmed by bees. However, they play a vital role in food production by pollinating about 30% of the world's crops as well as a large percentage of wild plants. Unless absolutely necessary, killing them should be avoided. If you have an infestation, you may have no other choice.
Most of the time, carpenter bees pose no threat. They're large in size and can be startling, but they are solitary creatures that aren't dangerous unless provoked. The male carpenter bee is not aggressive and is born without a stinger. If provoked, the male has no defense that would be a threat so he tries to appear intimidating by darting and hovering around your head. Females do possess a stinger but aren't often aggressive. Any insect with a stinger has the potential to sting. If handled, female carpenter bees will sting. Left alone and without an attempt to harm them, the risk of being stung is minimal.
The life cycle of carpenter bees consists of four stages. The female uses her mandibles to make a 1/2" hole in wood to hide her eggs. She tunnels up to 6" into the wood and places the eggs inside. The larva stage occurs after the bee emerges from the egg. Carpenter bee larvae get food from the deposits the mother leaves inside the tunnels. The pupa cycle occurs when the bee goes into a metamorphosis stage before transitioning into an adult. The bee is still in the nest at this time so it doesn’t have build a cocoon; the transition takes place in the brood cell. The pupa stage leads to the adult stage and completes the average seven-week cycle. An adult's mandibles allow them to burrow out of the brood nest. A small carpenter bee transitions into adulthood quickly. The average female will lay 6-10 eggs and dies shortly after laying her eggs. Males die shortly after mating.
These bees are attracted by wooden structures such as decks, steps, sheds, and house trim. Outside wood piles can also lure them. If you want to deter carpenter bees from laying eggs in your home’s exterior, some methods work very well. Painting the exterior with a polyurethane coating stops them. Pressure-treated lumber, vinyl and plastic siding and trim will also deter carpenter bees.
You can also try luring carpenter bees away from your home to another location by installing a soft-wood post or bird house in a shady place near some flowering plants. This will provide a place for the female carpenter bee to lay her eggs easily as well as providing close proximity to a food source. Cedar, pine, redwood and cypress are soft woods the bees can easily drill into to deposit their eggs.
(photo: By Jbergner [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)], from Wikimedia Commons)
Carpenter bees normally emerge from their brood cells in August. During this time, the young bees are free to roam outdoors, but they often choose to stay in the general area where they were hatched. These bees don't die in the winter; however they do conceal themselves. Carpenter bees will often return to their place of birth and burrow back into their original brood cell for protection. If this location isn't nearby, they will sometimes enter the brood cell of another bee.
The biggest concern for homeowners is the damage carpenter bees can do to homes. Since the female can only lay up to 10 eggs in her lifetime, there is no concern that large nests or colonies of the bees will form.
(carpenter bee damage)
If carpenter bees choose your home to nest, you will need to fill their holes after they've been abandoned. There are several materials that can be used to plug the holes: steel wool, caulk, dowels, wood putty, and wood glue. The main goal is to fill the hole and paint over it. Filling the holes will keep the bees from reentering their brood cell in the winter. Preventing future drilling is the key to ensuring that the damage doesn't continue. Carpenter bees don’t eat wood, they actually feed on nectar and pollen. Carpenter bee holes are excavations that allow the females to burrow into the wood in order to protect her eggs from danger.
Carpenter bees are approximately 1/2-1" long. Most are black or blue, but they can also be greenish, metallic blue, and bluish-purple. They have a smooth abdomen and a noticeable black spot on their backs. In comparison, the bumblebee has a hairy abdomen, is not solitary, is defensive and will attack if the nest is threatened. Bumblebees usually have yellow markings that identify them. Males have yellow on their faces, which helps to differentiate the male and female bee. Yellowish hairs are present on the legs and thorax of both sexes. Carpenter bees lack these hairs, so these regions appear glossy. Small carpenter bees are often dark in color. A bumblebee has a broader body and a more rounded tip to the abdomen. Bumblebees have fewer or no stripes and usually have part of their body covered in black fur, while honeybees have many stripes including several grey stripes on the abdomen.
According to folklore, if you hear a carpenter bee buzzing near you, you will hear bad news. However, I always enjoy a carpenter bee buzzing around to look at me face-to-face. In Appalachian folklore, bees hovering close to people and even appearing to look into their eyes are said to be listening. After listening to the latest news, the bees take it back through the community sharing the information along the way. So be careful what you say around a carpenter bee because it just might be repeated all over town.