Campus News

Control carpenter bee colonies

About this time every year people see large, black bees hovering around their heads and homes. They’re probably carpenter bees, which slightly resemble bumblebees, but have bare, shiny and black abdomens. They build their nests in tunnels they create in wood. They chew a perfectly round hole about the size of a dime into soft, untreated, unpainted weathered wood.

Carpenter bees prefer bare softwoods, especially redwood, cedar, cypress and pine. They don’t typically bother painted or pressure-treated wood, according to Wade Hutcheson, Spalding County Cooperative Extension agent. To control them, he recommends a fresh coat of oil-based paint.

Where the bees already have attacked, spraying insecticide on the wood surface won’t work. It has to be injected into each burrow to be effective. An aerosol spray for wasp and bee control will work if it is directed into the hole. Applications of cypermethrin or permethrin may provide short-term control when applied to wood surfaces, but will have to be reapplied after one to two weeks to maintain control. After a couple of days, plug the hole with a piece of wood dowel coated with carpenter’s glue, wood putty or your choice of filler to protect against future use of the old tunnel. It’s best to spray at night to kill the adults and the brood. If nests are sprayed during the day, the adults may be gone. And they may just start a new colony.