Tom Turpin
Professor of
Purdue University


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Flies in the face of fashion

What's Buggin You Now?





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Carpenter Bees Good at Drilling Holes in Our Wood

A carpenter is a person who builds things from wood. Some people are carpenters by occupation. A few people even have the last name of carpenter--no doubt a testimony to some ancient relative who was good at working with wood.

Some insects are known for their work with wood, and, like humans, have carpenter in their names: carpenter bees, for example. These bees get their name not because they build things from wood but because they build their nests in wood.

Carpenter bees generally fall into two groups: small carpenter bees and large carpenter bees. In addition to their size, the habits of the two groups also differ. The small carpenter bees are dark-bluish in color and make their nests by excavating the pith from stems of bushes. Then, they nest in the tunnels produced.

The large carpenter bees resemble bumble bees. Both types of bees are about the same size with the basic yellow and black colors. There are differences, however, between these bees.

Bumble bees live in colonies with a queen and many workers. Carpenter bees have a solitary life, one bee per nest. Bumble bees will sting when they or their nest is threatened--a behavior many unlucky humans have discovered over the years. On the other hand, carpenter bees seldom sting, even in defense of themselves or their nest.

Bumble bees and carpenter bees do look slightly different. Bumble bees are fuzzier than carpenter bees. The abdomen of the carpenter bee is almost bare. Also, the large carpenter bee has a white spot on the front of the head. So, when you are face to face with a carpenter bee, you can identify it by the white spot.

Carpenter bees zoom around their nesting area in short, rapid flights. They frequently stop and hover in the air, turning around as if surveying the landscape. Or, as some folks think, looking for someone to sting! But it is all bluff; the males can't sting and the females seldom do.

Most of us encounter carpenter bees when they go about their business of making a nest in wood. Frequently, that wood is part of the structure of our house, barn, shed or fence. Most of us are unhappy about the prospect of sharing our wood and immediately try to discourage those brazen bees.

So what is going on anyway? The carpenter bee chooses a site that will provide enough space for its home. That generally means a board at least 1 inch wide by 4 inches deep. It then drills a vertical hole about the size of a standard lead pencil in the wood. Once inside the wood an inch or so, it turns at a right angle to chew out a nest chamber.

The nest chamber can be up to 6 inches long. At the end of the chamber, the bee will store pollen and lay an egg. The cell is then separated from the next cell with a plug of chewed wood. This continues until the chamber is filled with provisioned cells with eggs. The eggs hatch, and the larvae feed until they pupate.

Sometimes, the carpenter bee will produce cells both left and right of the entrance hole. All of this results in chewing of wood. Sometimes the sawdust piles up below the entrance hole. And sometimes humans can actually hear the bees chewing the wood. This all adds up to concern about the damage that the bees are doing. Generally, the potential for damage is minimal, but most people try to get rid of the insect carpenters anyway.

What is the best approach to eliminating carpenter bees? Spray a little insecticide in the entrance, and use wood filler to close the hole. Oh, by the way, if you have redwood around, it will be the favorite of the carpenter bees. There is just something about chewing in redwood that makes these bees happy. But, then, what carpenter wouldn't enjoy working with redwood if given the chance?



Writer: Tom Turpin
Editor: Olivia Maddox