Carpenter bees are often seen buzzing around your backyard garden or wooden patio deck in the warmer spring and summer months. Like other native bees, these insects are essential pollinators for native plant communities. They can also play an important role in crop pollination. Carpenter bees are often confused with bumble bees because of similarities in both size and color. However, they can easily be distinguished because carpenter bees have smooth shiny black abdomens without fuzz whereas bumble bees tend to be fuzzy all over. Despite their parallels in appearance, the nesting habits of these two types of bees are quite different. Carpenter bees nest alone in tunnels chewed into wood while bumble bees live in small colonies that usually nest in the ground. Both types of bees can be beneficial, but carpenter bees can be destructive when nests are constructed in the sides of homes, wooden decks, fence posts, or other wooden structures.
Carpenter bees get their common name from their nesting habits. Eastern species of carpenter bees prefer to nest in soft woods such as cedar, redwood, cypress, pine, and fir. Western species are more commonly found nesting in hard woods such as oak, eucalyptus, and redwood. Despite their preferences, all species of carpenter bees are much less likely to nest in painted or pressure treated lumber of any type.
Carpenter bees overwinter as adults in nest tunnels and emerge in mid to late spring. After mating, the female locates a suitable nest site and begins by chewing a perfectly round entrance hole into the wood. She then excavates tunnels about five inches long that are provisioned with balls of pollen to serve as food for the larvae, and the tunnels are sealed. The larvae feed and develop in the tunnels before emerging as adults in late summer and the process begins again. Mated females may enlarge and reuse old nest tunnels for egg laying or excavate new tunnels. Considerable damage can occur to wood that has been utilized as a nesting site year after year.
Knowing how to identify carpenter bees and their nesting habits is key to protecting your home and your property from costly wood damage. First, you can recognize the entrance to a carpenter bee nest because the hole is about a half inch in diameter and looks perfectly drilled. Second, carpenter bees make quite a mess when excavating a nest by leaving deposits of leftover wood below the hole. They also can cause noticeable staining to the area outside the entrance with yellow/brown pollen and feces. Lastly, male bees are often seen hovering around or just outside of the nest entrance in order to protect the female that is busy inside the nest. So, spotting a hovering carpenter bee could indicate a nest is nearby.
Both male and female carpenter bees can be territorial and may dive bomb anyone that comes near their nest. However, female carpenter bees rarely sting unless provoked. Males do not have a stinger and do not sting at all. Still, most homeowners do not want to have aggressive bee-like pests around that can damage their home. Make sure to contact your pest management professional when you see signs of carpenter bees on your property in order to treat and prevent further carpenter bee damage to the wooden parts of your home.