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C.
Roach, UGA CAES 
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| YOU’D THINK THEY
BUILD, like their name implies, but carpenter bees can cause a lot of damage in wood siding and facia board. UGA scientists say the troublesome bees drill an inch into the wood, then tunnel along with the grain for 4 to 6 inches. They often reuse the same area, and tunnels may reach 6 to 9 feet. |
Carpenters bees are hard at work in Georgia houses. For all
their industrious
drilling, though, they have little benefit to people, say University
of Georgia experts.
“They have little beneficial effects to offset their more
obnoxious habits,”
said Keith Delaplane, a UGA Extension
Service entomologist.
Good at some
things, really good
at one thing in particular
“They aren’t very good pollinators, and they’re actually
flower robbers,”
he said. “They suck out the nectar from a flower without
pollinating
it. They have short tongues and have to bite through the
flower to reach the
nectar. About the only thing they are good pollinators for
is passion fruit.”
What they are good at is chewing holes in eaves. “If you
get a long-lasting
population, they could weaken the timbers,” Delaplane
said.
What to look
for
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C.
Roach, UGA CAES 
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| SAWDUST MAY BE
THE FIRST SIGN OF DAMAGE (lower left corner.) Once you see it, treat quickly to prevent reinfestation. For any treatment to work,though, it must be squirted into each hole. Night treatments are most effective because that’s when you can be more sure adults are in their hole. |
Carpenter bees look like bumblebees, except they don’t have
any yellow on
their abdomen. They’re black with areas of yellow hair and
are usually about
an inch long. Usually found in porch ceilings, window sills,
door frames,
headers and siding, they fly or hover without regard to
people around.
The troublesome bees chew half-inch round holes in wood.
Usually, the first
noticeable sign of an attack is the sawdust. They don’t
usually drill in decayed
wood or wood with bark. They prefer soft woods like southern
yellow pine,
white pine, California redwood, cedar, Douglas fir and
cypress.
They drill an inch into the wood, then tunnel along with
the grain for 4
to 6 inches. They often reuse the same area, and tunnels may
reach 6 to 9
feet.
Causing
problems
“Over the long term, it is possible for them to do severe
damage,”
Delaplane said. “They nest in the same tunnels year after
year. Each
generation carves its own nest partitions. They chew the
inside of the tunnels
and make paste to create their own nests.”
Since they have very little environmental benefit, control
is a homeowner’s
best option.
Controlling bees
requires two
things
“They’re fairly easy to control,” Delaplane said. “It
requires
a ladder and pressurized insecticide.”
Roach, UGA CAES
Spraying insecticide on the wood surface won’t work. You
must inject it into
each burrow to be effective.
“You can spray any time of the year, but right now is
probably the most
effective time because the holes are active and you can tell
which holes should
be treated,” he said. “If you see sawdust or feces,
spray.”
Delaplane recommends spraying at night to kill the adults
and the brood.
“If you spray during the day, the adults may be gone,” he
said.
“And they will just start a new colony.”
After injecting the insecticide, plug the holes with caulk
or wood putty.
“They don’t like paint,” Delaplane said, “so painting after
caulking will help.”
