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What is it?

These insects are bees of the xylocopa species, which feed on decks, posts, rafters, beams and other wooden structures in and around the home.

What does it look like?

Carpenter bees are a metallic blue or black. They make a distinct buzzing sound as they fly around the house or yard. They are typically larger than other bees in size and only the females sting if handled. Male bees may be frightening due to their loud buzzing, but do not sting. Nests look like partitioned cells of paper and should always be approached with caution. They build their nests around wooden structures, and leave 1-inch wide holes through which they enter and depart the nest.

How does it manifest?

Female carpenter bees create galleries partitioned off into small cells where bee larvae mature. If a nest is approached, the male bees will buzz around the head of the intruder. As long as you do not swat at or try to handle the bee you will not get stung, just buzzed. Wood structures may become weakened if bee tunneling occurs year after year as new galleries are formed.

What can you do about it?

Once you find a nest infested with carpenter bees you can treat the exposed wood and gallery holes with chlorpyrifos containing insecticides. Holes should then be sealed with putty, caulk, dowel pins or plastic wood resins to prevent bees from returning to their nest. As a preventative measure, painting exposed deck boards, beams, rafter and posts once a year will prevent bee tunneling and infestation.