Question: I have heard that carpenter bees can cause a lot of damage to wood structures, and I have noticed a lot more bees around my house this year. How can I tell if I have carpenter bees or bumble bees?
Answer: During the spring and early summer, people often see large black bees hovering around the outside of their homes. While there is a high probability these are the destructive pests you are trying to avoid, carpenter bees and bumble bees are often mistaken for each other. Both are large, imposing insects, up to an inch long, with bright yellow and black coloring on their bodies. However, they do have very different characteristics that make them easy to identify.
Carpenter bees can be differentiated from bumble bees by the abdomen. A carpenter bee has a slick, shiny black abdomen. The thorax, located directly behind the head, is usually covered in yellow, orange or white hairs.
In contrast, the bumble bee usually has a hairy abdomen with black and yellow stripes. Common eastern bumble bees, designated as New Jersey’s native pollinator in 2017, are abundant in this area and have black hairs on their head, abdomen and legs. Their thorax is yellow.
The nesting habits of these bees are, especially for homeowners, one of their most important distinguishing characteristics. Bumble bees are social insects that live in colonies, usually in woodland areas and fields. Their nests are most often found in the ground in abandoned rodent nests or similar areas. Carpenter bees, on the other hand, are solitary bees, preferring to nest alone in wood tunnels. The female carpenter bee will build a nest in unpainted, untreated wood, boring a finger-wide hole that can extend 6 to 10 inches deep to lay its eggs. They prefer weathered wood, especially softer varieties such as redwood, cedar, cypress and pine. While they do not consume wood, their tunneling can be very destructive. Much to the dismay of many homeowners, common carpenter bee nesting sites include eaves, rafters, fascia boards, siding, wooden shake roofs, decks and outdoor furniture. Painted surfaces are less susceptible to being used by carpenter bees as nesting sites.
Despite their similar appearance, the behavior traits of these bees are also very different. Bumble bees are generally very docile insects, though they can and will sting if they feel their nest is in danger. A carpenter bee disturbed in the wild is likely to put on a territorial show of aggression but, this is the behavior of a male bee and he cannot sting. A female carpenter bee can deliver a painful sting but rarely does unless she is protecting her nest in a piece of wood or is being physically handled.
Carpenter bees, particularly the eastern carpenter bee, are considered a destructive nuisance insect and are quite often the target of pesticides to prevent damage to homes and other structures. However, both carpenter bees and bumble bees are very powerful pollinators and serve an important role in our ecosystem. Both are excellent pollinators for fruits, vegetables and many other crops. In fact, common eastern bumble bees are one of our most important pollinators for major crops in New Jersey such as blueberries, cranberries, tomatoes and peppers. These bees are also often used in commercial greenhouses to pollinate plants grown in them.
To deter carpenter bees without pesticides, keep exposed wood surfaces, including nail holes and saw cuts, coated with polyurethane or oil-based paint. Consider using nonwood building materials, such as vinyl siding, to avoid possible damage by carpenter bees. If tunnel entrances are found in buildings, seal tunnel entrances immediately with caulk.
For more information on carpenter bees and bumble bees you can contact your local extension office. Atlantic County residents can contact the Master Gardener Helpline at 609-625-0056. Cape May County residents can call 609-465-5115, ext.3607.
Events: Atlantic County Master Gardeners will be available to answer gardening questions and take samples for plant identification or diagnoses throughout the county this summer. You can find us at the Ventnor City Farmers Market, July 19 and Aug. 8; Galloway Green Market, July 25; Brigantine Farmers Market, July 13; Atlantic County 4-H Fair, Aug. 8, 9, and 10; and Brigantine Green Fest, Aug. 24.
Do you have a gardening related question you would like answered here? Please forward your questions to Belinda Chester, Master Gardener Program Coordinator, Rutgers Cooperative Extension Office, 6260 Old Harding Highway, Mays Landing, NJ 08330. You can also submit questions at Rutgers-atlantic.org/garden or email them to firstname.lastname@example.org; please include “garden question” in the subject line.