It's always interesting to get inquiries from people about bees hovering around their decks, gutters or siding. Some are amazed to find perfectly round 3/8" holes that look as if a vandal had done damage.

This little "vandal" is a carpenter bee. A carpenter bee looks similar to a bumble bee. Here are the differences between the two:

• bullet Carpenter bees have a shiny abdomen, hairless upper abdomen surface with yellow colored hairs on the mid-section or thorax while bumble bees have a hairy yellow upper abdominal surface
• bullet Carpenter bees nest in wood whereas bumble bees nest in the ground.

Though carpenter bees are very large and intimidating, unlike their wasp relatives (hornets and yellowjackets), they are not generally aggressive. Though capable of stinging (females only), these insect don't usual sting unless provoked.

Carpenter bees are very interesting in that they will enter primarily unpainted softwoods such as pine and chew that nice, 3/8" entry hole. After chewing a relatively short entrance, the bee will chew another tunnel, several inches long at a ninety degree angle to the opening where a female will lay eggs starting from the back, working toward the gallery opening.

These bees will nest in the wood. There is typically one generation of these insects annually with most of the activity in the Spring. These bees are known to return to previously used galleries from year to year, although other bees can make new galleries as well.

The most common sites for these intruders include fascia board (often behind the gutters), deck railings, unpainted lawn furniture, posts and unpainted playground equipment.

Carpenter Bee Management

Some people don't mind these insect that much. As with other bees, they are beneficial as pollinators of flowers. However, other people are not as happy to have carpenter bees around and seek ways to eliminate the bees.

There are two ways of dealing with the problem: exclusion and pesticides.

Exclusion is done by sealing and then painting the wood surfaces well. A good enamel or polyurethane is probably most durable and is least likely to be attacked again. Another solution is to wrap exposed wood with aluminum flashing in areas such as the gutter fascia.

The most effective pesticide application for existing, active Carpenter Bee galleries is dust. The big advantage of dust over sprays is that the application targets this pest only with virtually no affect on non target organisms such as people or their pets.

There are several such products on the market for this pest. The best are non repellent products such as carbaryl (Sevin) dust and boric acid (Borid Turbo Aerosol). We sell Apicide, a carbaryl dust product and Borid Turbo (boric acid) for those wishing to treat the problem. Either of the two products may be applied into the entrance of an active carpenter bee gallery. Only a small amount is needed for each gallery opening.

Commercial applicators can apply insecticides in a wettable powder formulation (a powder that suspends in water) that will repel and kill carpenter bees. The active ingredient, cypermethrin, is sold under the Demon WP and Cynoff WP trade names. This type of application is helpful where there are a lot of Carpenter Bees hovering around. We do not offer these restricted use products products for sale to the general public.