Does it look like a bumble bee? Does it suddenly disappear under a ledge or eave? Is there a perfectly round hole near where it disappeared? Is the little hole in the bottom side of the trim or structure board? Is the wood bare, need painting, or stained wood? Is the wood cedar, redwood or some other soft wood? If the answer to most or all of these questions is yes!, then you probably are providing a home for a carpenter bee.

 The most common group of carpenter bees in this part of the country resembles bumble bees. They are about the same size, have yellow markings on the thorax (middle part of body) like the bumble bee, but are much darker in color and the abdomen mostly black and bald; gives the appearance of being shiny.

The burrow opening is a round hole in the wood about a 1/2 inches in diameter. The precision of the cut will make you think it was done with a drill. When the female is actively constructing the burrow and brood chambers, you should be able to observe a small pile of discarded wood shavings directly below the single entrance/exit hole.

After a carpenter bee female has set up housekeeping and after the young-of-the-year become adults the outside of the burrow hole will show brown and/or yellow staining. This is bee excrement.

 Structural wood that is the most inviting to a female carpenter bee is either a horizontal or slanting board of soft wood (e.g., cedar or redwood) with little or no paint. If you have siding, eaves, wooden shakes, porch ceilings, windowsills or doors that have these characteristics you are inviting a visit from a carpenter bee each spring.

The physical damage is a vertical round shaft with 2-6 horizontal brood chambers connected to the entrance/exit burrow. Depth of the main burrow will be about 3-6 inches. Besides constructing new nesting sites, female carpenter bees will also use galleries from previous years.

Even though carpenter bees are equipped with a stinger they are quite docile. About the only thing that will provoke stinging behavior is being handled and petted.

If you have carpenter bees burrowing into a wood surface of your home dust or spray burrow entrances to nest with an insecticide dust labeled for this problem.

It is best to treat nests when you first notice activity around the hole. The insecticide dust will easily kill both the adults and "uncapped" brood chambers.

You may need to treat again in August when new adults emerge and become active. In the fall, fill the burrow holes and paint or varnish the entire wood.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

 

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