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6-13-02
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?
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