For Release May 16, 2004

Bees in the Boards

AGRI-VIEWS
by Chuck Otte, Geary County Extension Agent

Bees and wasps are truly incredible creatures. Some form huge colonies, some are solitary nesters, some are very docile, and some are very aggressive. And we have representatives of all the above right here in our part of Kansas.

The past couple of weeks we have seen a lot of activity of carpenter bees. Carpenter bees are large solitary bees that look a lot like bumble bees. The main visual difference is that bumble bees are covered with hair and carpenter bees are not. The abdomen, furthest back body section, of a bumble bee will usually be yellow and hairy. In a carpenter bee the abdomen is black and shiny. In some of the bumble bee species the abdomen is black instead of yellow, but in a bumble bee the abdomen will always be hairy.

Bumble bees usually nest in the soil and are a social insect with small to medium sized colonies. Carpenter bees nest in wood and are solitary nesters, although you commonly find several females nesting in the same vicinity. Female carpenter bees burrow nearly perfectly round holes into unpainted wood. This entrance hole goes in about one inch and then turn sharply, boring with the wood grain for four to six inches.

In these tunnels, the female will place pollen and nectar mixed together along with one egg. She'll seal this egg cell up and make another one, often as many as six to eight in a tunnel. Then she'll leave, the young larvae will feed on the food left behind and pupate into an adult in the late summer, usually August. The adults that emerge in the late summer will spend the rest of the fall feeding and finding a place to overwinter. They won't mate until next spring.

While the female is busy gathering food and laying eggs, the male carpenter bee is hanging around the nest hole, waiting for a chance to mate with the female. As in all bees, the female has a stinger, but rarely uses it, and the male has no stinger. The males can get very aggressive and will often hover in front of people or buzz around them.

Carpenter bees can cause structural damage in wood because of their nest tunnel boring. If you have carpenter bees one year, you'll probably have them a second because they'll keep coming back and using old nest tunnels. They'll frequently also cause staining on the wood around the nest tunnel.

Carpenter bees rarely attack painted wood so try to keep all exposed wood painted. Wood stains are not an effective deterrent, so consider treating undersides of elevated decks with a natural deck paint, not stain. To treat an active nest tunnel, wait until after dark and then spray into the tunnel with aerosols or dusts. Do not plug the holes so that the carpenter bees can come and go and make contact with the insecticide.

Then in August, as the new carpenter bees are starting to emerge, treat the holes again to control the new brood. Then a few days after that, you can plug the holes with wooden plugs, caulking, or wood putty. This is necessary to discourage future use in coming years. Be sure to follow up and paint these exposed surfaces that the bees are attracted too.

Carpenter bees are more common this spring than I can remember in a long time. While they seem threatening the really aren't, but to protect the wood in your house, deck or outbuildings, control may be necessary!

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