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John Fulton

John Fulton
Former County Extension Director

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In The Backyard

Horticulture columns and tips done on a timely basis

Carpenter Bees

Posted by John Fulton -

Carpenter bees will be the unofficial "insect of the week." What is usually a very minor pest, has garnered half-a-dozen calls and office visits in the last week or so. There are many species of carpenter bees, with the most common in our area resembling a bumblebee. There are differences of course, with the major one being the top of the abdomen segment of the carpenter bee being bare and shiny. Like any bee or wasp, the males can't sting. They do however try to intimidate you. The females are rather tame, but do have the ability to sting if you provoke them too much (such as trying to catch them).

What sets the carpenter bee off from other bees we are more familiar with is – well, just what its name implies. It works wood. Wood isn't a food source, but rather a place to lay eggs. The bees chew a hole in wood, and this initial hole becomes a tunnel with different chambers. This same area is used over a period of years, and when it is outgrown, a new set of tunnels is formed. The take-away is carpenter bees return to the same area – if not the same set of tunnels. If you see bees drilling wood, or a number of bees hovering around the eaves and soffit areas of the house, you can be somewhat certain you have carpenter bees.

Damage from a few bees is rather minimal, but remember the part about expanding the same area year-after-year. Over a period of time, there can be significant damage to certain boards. Another habit is the preference to drill up, but that isn't an absolute. There is usually more damage on soffit and fascia than on siding.

As for control, it gets a little difficult. Painting exposed wood surfaces tends to be a deterrent, but if a hole existed then the bees are used to the area. Use of dust formulations of insecticides are the most effective. They also are more labor intensive to use. Carbaryl (Sevin) dust is one of the more common ones, and is best applied through a dust applicator (looks like an old bicycle pump with a dust canister and plastic tube attached). Puffing dust into the holes in spring when you first notice the bees, again mid-summer, and a third time in early fall is the recommended schedule. Larger areas can be treated with sprayed insecticides such as permethrin, bifenthrin, or cyfluthrin on about the same schedule. These sprays will help reduce populations, but won't be carried into the tunnels as effectively as dusts. Don't plug holes immediately after treatment either. The idea is to have the bees carry the insecticide into the tunnels as they enter. 4-H Camp is battling these bees, and the Camp has resorted to covering soffit and fascia with metal after a period of fighting a losing battle.

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