Archive for Thursday, June 4, 2009

Carpenter bees must be stopped to reduce damage to home exterior

June 4, 2009

I think we are all used to watching out for bumble bees, and letting them have their space, but there is another bee that is fooling us into treating it like a bumble bee. This imposter bee looks almost identical to a bumble bee, but is known as the carpenter bee. It will fool you into fearing there are bumble bees around your home, and can cause you to overlook damage that carpenter bees are doing to the outside of your house. If you’ve noticed half-inch wide holes in the outdoor woodwork around your house, you are seeing the damage caused by carpenter bees.

Carpenter bees, commonly called wood bees, bore holes into wood to live and lay their eggs. If left alone, they can do major damage to eaves, window trim, wood decks, outdoor furniture and the framework of barns and sheds. They prefer to attack bare wood that has weathered some, is unpainted and has not been treated. They also prefer soft woods such as pine, cedar and redwood, but have been known to attack virtually all kinds of wood.

The best way to prevent carpenter bee damage is to paint all exposed wood surfaces. Stains and varnishes help some but do not prevent damage as well as paint. If you have a preexisting hole that is being used by the bees, you can treat the hole with an insecticide that has some residual activity. Carbaryl-containing insecticides, such as Sevin, work well for this. You need to treat the hole at night or late evening while the bee is there, then leave the hole open for a few days to allow bee activity. The holes can then be plugged with caulking or wood-filler to prevent further use and to reduce wood decay around the damaged area.

Now that you can recognize, prevent and treat the damage caused by carpenter bees, here is the best way to distinguish them from bumble bees. The main difference between bumble bees and carpenter bees is found on the abdomen, or the rear end of the bees. Carpenter bees have black, shiny abdomens, while bumble bees have fuzzy abdomens that tend to be black and yellow.

Carpenter bees are less aggressive in general than bumble bees, but still can harass people. Male carpenter bees will hover around your head in defense of their territory, but are unable to sting, so it is all for show. Female carpenter bees do have the ability to sting, but typically only do so if they are handled or pestered. Whether they sting or not, if you have large bees buzzing around, it is cause for concern.

If you have questions about this article, carpenter bees and bumble bees, feel free to contact me at the Leavenworth County Extension Office on the corner of Hughes and Eisenhower roads in Leavenworth or call (913) 250-2300. I can also be reached via email at


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