Carpenter bees must go

Q. Carpenter bees were attacking my pergola and dive bombing me earlier this summer. What can I do to get rid of them?

Mary from New Castle

A. Carpenter bees can be annoying. They are named so because females excavate wood galleries to create nest sites for their young.

They do not eat the wood, this is just how they make a nesting site. They can be quite frightening because they are large – most nearly 1-inch long.

While the dive bombing is annoying, these large bees are important native pollinators. They feed on pollen and nectar from plants in our gardens and landscape. The males are the ones that are aggressive, not the females.

While males are aggressive, they lack a stinger so they won’t sting you. While females do damage wood, they are actually harmless to humans. Females do have a stinger, but they only sting when they are handled roughly or provoked to sting.

Carpenter bees resemble a bumble bee, but its abdomen is shiny, black and hairless.

They prefer bare, unpainted and weathered softwoods, especially redwood, cedar, cypress and pine. So, painting or staining the pergola would be a best bet to prevent them from setting up shop again in this area of your backyard.

Avoid killing them if possible. Instead, repair the wood and make it less attractive to them. The bees will often return to the nesting site, so when the holes are empty after the eggs have hatched in the fall, fill them with caulk or hardwood putty.

Steel wool can also be placed in the holes to discourage new occupants next year. Painted and pressure-treated woods are less prone to attack.

The eggs the females laid in these holes will hatch soon. It only takes three months for the new adults to emerge from those holes. Wait until these new adults emerge before closing off the holes. This will encourage them to find a new site to overwinter.

For information, visit http://go.osu.edu/carpenterbee.

Hugh Earnhart, an OSU Ext. master gardener volunteer in Mahoning County, answered today’s question. Call 330-533-5538 to submit your questions. Regular clinic hours are 9 a.m. to noon Mondays and Thursdays.