Just when Southerners thought they’d seen the last of El
Ni¤o’s effects, in come the
biting blackflies.
“Blackflies are interesting pests,” said Ray Noblet, head of
the entomology
department of the University of
Georgia
Environmental Sciences.
“There are lots of misconceptions about them.”
Typically, blackflies aren’t as prevalent in the South as
they are in the Northeast or
Northwest. But thanks to the El Ni¤o-induced wet weather this
winter and spring, they’re
here in force.
“We’ve had an outbreak of blackflies where we haven’t had
them in years,”
Noblet said.
El Ni¤o can’t take all the blame, he said. Give credit to
better water quality, too.
Blackflies can’t breed in polluted water.
“Streams that didn’t have blackflies because of pollution
problems 20 years ago
have been cleaned up,” Noblet said. “Now they breed readily, and
you see large
populations of blackflies.”
Blackflies aren’t like mosquitos, which breed in standing
pools of water.
“The water has to be flowing for blackflies to live in it,”
Noblet said.
“You will find them anywhere adjacent to rivers and streams. You
can see them around
ponds where there is a stream leading from the pond or an active
spill way.”
The small, dark, stout-bodied flies are about half the size
of mosquitos and are often
mistaken for gnats. But they aren’t.
“They swarm around your head,” Noblet said. “But they’re
bigger than the
eye gnat Southerners typically have to deal with. They’re pretty
hard to identify without
a microscope.”
You can, however, tell a blackfly by its bite.
“They have biting mouthparts much like a deerfly or
horsefly,” Noblet said.
“They cut a hole in your skin and suck the blood that pools
after they make a
wound.”
Ouch!
Those in south Georgia who thought living below the gnat line
was bad enough now have a
new worry.
“We’re seeing them down there this year,” Noblet said. “We’ve
even had
calls from Florida. Early in the summer they had high numbers in
the Tampa Bay area, where
we’ve never heard of them even talked about before.”
Getting rid of them is a problem, too. By the time you see
the flies, it’s probably too
late to control them.
“A successful control program must be directed at the larval
stage,” Noblet
said. “And it has to be started in advance. The main thing you
try to do is interrupt
the breeding at the larval stage. It’s hard to kill the adults.
You can fog like you do
for mosquitos, but they’ll just fly in again.”
A new biocontrol agent is now on the market.
“It’s a new bacterium or Bt (Bacillus thuringiensis var.
israelensis)
like those used to control a lot of insects. But this one is
specifically for flies and
mosquitos. It works great,” Noblet said.
“It’s not a chemical pesticide, so it doesn’t pollute streams
or damage water
quality,” he said. “But you have to cover a wide area, because
they will fly
three, four or five miles.”
The biocontrol is more for golf courses or horse camps that
need to cover a large area.
It won’t work well for your own backyard.
This summer’s dry weather may prove to have the best solution
for the blackfly problem.
“Populations will begin to tail off fast now,” Noblet
said. “By late
July to early August, we should see things improve. The dry
weather will help. A lot of
the streams breeding them now will dry up by then.”
