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Mosquitoes: Summer rains dampen breeding season
By Jason Lesley
Mosquito season arrived just last week in Georgetown County.
It’s hard to believe when the little blood suckers attack relentlessly during warm weather, but this has been a very mild year for mosquitoes so far, according to Tim Chatman, supervisor of the Georgetown County Department of Public Services Mosquito Control Division.
“If you go out at dusk, you are going to get bitten,” Chatman said. “I don’t care where you are in the county, but on the Waccamaw Neck, it’s been one of the mildest seasons since I’ve been here.”
Heavy rainfall experienced from June through August served to disrupt the life cycle of the area’s most prevalent mosquito, the salt marsh breeder, Chatman said.
“Everything we do is centered around the weather and water,” he said. “Mosquitoes need it to survive and produce, and they do a pretty good job of it. We’ve had so much rain, it served to wash some of the egg deposits out of the area, which explains why we’ve had a relatively mild season.”
Chatman said the mosquito species that breeds in flood water and forested areas has been more prevalent than the usual two varieties of salt marsh mosquitoes.
After seven inches of rain in late August, the weather has been dry for two weeks. “Couple that with a lunar high tide, and you are going to get some breeding,” Chatman said. “Put those two elements with high temperatures, and you have mosquitoes. That’s exactly what we had last week.”
Chatman said his department went from a half-dozen mosquito complaints a day to over 100. Studies showed mosquitoes were still hatching as the complaints grew, so Chatman waited two days before sending up planes to spray. “If we had sprayed on Monday,” he said, “we’d be spraying again on Wednesday. We made the decision to wait on the mosquitoes to hatch and flooded them day and night.”
Mosquito season here runs through October, Chatman said. “September is normally a good month for us for mosquitoes,” he said. “This is when we keep high temperatures and get late season storms. We could still see some heavy mosquito activity.”
Georgetown County spends $570,000 a year on mosquito control, with $290,000 of that going to chemicals and their application. In addition to Chatman, the department has two inspectors and one administrative person working at the Georgetown County Airport.
Chatman, a Georgetown native, worked as a mosquito inspector for the county after graduating from Coker College with a business degree in 1979. He left to join Georgetown Steel but never forgot what he had learned. “It was field work, scientific work, very interesting things you learn about mosquitoes,” he said.
After the steel mill shut down in 2003, Chatman worked in hospitality before the supervisor’s job was posted. “I always enjoyed this job,” he said. “Since I’ve been back, it’s more rewarding. You get to help a lot of people.”
Chatman says the county’s program is one of control rather than elimination. “We won’t eliminate mosquitoes in Georgetown County,” he said. “We are blessed with a lot of water, and as long as we’ve got habitat we’ll have mosquitoes.”
Chatman said Charleston, Beaufort and Savannah, larger mosquito districts, have the resources to drain mosquito producing areas. “If you can drain, you can control,” he said. “Ours is not a program where we can do that. We try to be more proactive. Larviciding is a technique we use, getting the mosquitoes before they turn to adults. If we can get them in the larvae state, it’s easier and more cost effective.”
Chatman mixes larvicide with sand for application by air. The chemical falls on water, activates and prevents the larvae from developing into an adult. “Without wings,” he said, “they can’t get to us.”
Once mosquitoes become a plague, Chatman has to resort to pesticide spraying by air. The county contracts with Williamsburg Air Service for the applications. Pilots fly to Georgetown Airport from Kingstree to be loaded with pesticide.
There are limits to its effectiveness, he said. The droplet must strike a mosquito to kill it. Temperatures above 84 degrees cause thermal inversions that keep the spray from falling to the ground. Rain showers make spraying ineffective, too. The residual drops begin to break down as soon as they strike the land’s surface.
“It’s not like a home coating treatment,” Chatman said. “I research labels every season trying to find the safest, most effective chemicals we can use. People say that’s good, trying to keep the population safe, but we have to handle the product ourselves. We suit up to load trucks, wearing respirators in 90-degree heat. Those things are hot.”
The county has a policy to protect honeybees, warning beekeepers in advance of spraying schedules. “We know they are the primary pollinators and try not to harm them,” Chatman said. “We try to spray pre-dawn and after dusk to avoid those beneficials normally foraging in the daytime.”
Chatman said Georgetown has the second largest mosquito control program in the state, trailing only Charleston County.
“I’m proud of the program we have here in Georgetown County,” he said. “We are considered a small program, but compare us to Charleston and we do everything they do on a smaller scale. Charleston made its first mission this past weekend. They hadn’t done anything from the air because of rain. Their director said she’s never seen a season like this one.”