CARPENTER BEES
These are large, attractive looking bees with
a blue-black, green or purple metallic sheen. They
often burrow galleries into the exposed dry wood
of building, telephone poles, fence posts and bridges.
Carpenter bees resemble bumble bees, but they are
not social insects, and most of the top part of
their abdomen is without hairs. There are seven
species of carpenter bees within the United States,
of which an eastern species (Xylocopa virginica)
is probably the most destructive.
The males are at times annoying because they will
fly around the heads of humans. Since they lack
a sting, they are entirely harmless. The females
do possess a sting which they use very rarely.
While the damage to wood from the drilling activities
of a pair of carpenter bees is slight, the activity
of numerous bees over a period of years can cause
considerable damage. They often attack such objects
as window sills, wooden siding, eaves, railings,
outdoor furniture and fences. The entrance hole
(about ½ inch) is usually against the grain.
When the tunnel is about 1 inch deep, the bee turns
at a right angle to the initial hole and then tunnels
with the grain. Galleries usually average 4 to 6
inches in length, but can go up to 10 feet in length.
The female excavates the gallery by means of her
mandibles. She can excavate 1 inch in six days.
A single egg is deposited in a cell within the gallery
and is then sealed with honey-pollen and bee bread.
There may be a number of such sealed cells in a
linear row within one gallery.
The bees are solitary by nature, but may colonize
within the same piece of wood causing extensive
damage. The males and females over winter in old
nest tunnels and survive the winter if it is not
too severe. The adults emerge in spring, mate and
then the female deposits her egg. The larvae and
pupae develop during the summer and the adult bees
emerge in late summer.
A carpenter bee infestation is often first detected
by finding large amounts of sawdust on the ground
below the area being drilled. To control carpenter
bees an insecticide is dusted into the entrance
holes. The holes should not be plugged immediately.
The bees should be allowed to pass freely through
the entrance where they will contact the dust and
distribute it within the tunnels. Any newly matured
bees will emerge through the openings and contact
the dust there. In the fall, the holes can be filled
and the entire wood surface painted or varnished.
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