Friday, August 31, 2012
Rain was still falling at the Georgetown County Airport this week, but Tim Chatman called it “the calm before the storm.”
For six years, Chatman has been supervisor of the county’s Mosquito Control operation, housed at the airport, and he knows the blood-sucking pests probably better than anyone else in the county. He spends his days studying them and knows well the breeding and feeding habits of each of the 30-35 species found in Georgetown County.
“With all the rain we’ve had out there, we’re anticipating a big increase in mosquito breeding in the next few days, as soon as this rain gets out of here,” Chatman said. “But we’re prepared. As the numbers increase, we’ll have trucks running in certain areas, but we’re also anticipating putting up some more planes.”
The office normally has spray trucks loaded with pesticides rolling five nights a week during the season. Higher than normal volumes of mosquitos call for aerial spraying, a service for which the county has a contract with an outside vendor.
Both are subject to the constraints of the weather. If the wind is too strong, it’s raining or it’s too hot, the pesticides won’t be effective.
To determine which course of action is needed at a given time, Chatman and his small staff use trapping results, landing count rates and information from the public they receive through a service request line.
When the numbers increase over a certain threshold, we’ll pull out the big guns,” Chatman said. That means aerial spraying, which is reserved for higher population areas.
With landing counts the threshold is 12-15 adult, biting mosquitos per minute. Other districts have much higher thresholds, Chatman said, he likes to take care of the problem before it becomes serious.
The Mosquito Control operation in Georgetown County is small, with a staff of just four, but is one of the busiest in the state, falling behind only Charleston and Beaufort counties, Chatman said.
The office has a tiny lab where staff uses microscopes to study mosquito specimens, looking for new species coming into the area.
The lab is also where specimens of species known to carry West Nile virus are stored before being sent to Columbia for testing.
So far, no mosquitos trapped in the county have tested positive, but the county is keeping a vigilant eye on the situation.
Georgetown County has five species of mosquitos that could carry West Nile and Chatman and his staff use gravid traps to catch specimens for testing. The traps are set up in an area identified as a prime breeding ground for the virus.
The county also uses light traps for other species of mosquitos. Those devices are placed at 14 sites around the county.
Mosquito Control hasn’t found any new species in Georgetown County in recent years. The ones already identified offer trouble aplenty.
The two “dreaded nuisance mosquitos of this coastline” are both found in Georgetown County, Chatman said. Those are the golden and the black varieties of the salt marsh mosquito. They breed in very high volumes, and dredge spoil sites, of which there are about a dozen in the county, are favored habitats. The county’s Mosquito Control program was actually set up to combat those two types of mosquito in the 1970s.
However, “Enemy No. 1” for the program is the Asian tiger mosquito. It’s a container-bred variety, which means it’s a problem in every area of the county – and probably every backyard.
Education is generally the best tactic for combatting that species.
“It’s getting the homeowners to realize they can do a lot in protecting themselves and preventing a lot of the big mosquito problems just by emptying water from containers around their house – any container holding stagnant water. By eliminating these areas, we cut down on the number of mosquitos,” he explained.
Chatman’s office has also had success using gambusia, more commonly known as mosquitofish. They eat mosquito larvae from ponds and other water bodies, and are common in the county. Chatman keeps a supply in a tank outside his office to be introduced in certain areas if the fish aren’t already present.
To request mosquito control service in Georgetown County, call 545-3615. Residents can also dial that number to request to be notified before mosquito spraying takes place in their area.
For more information, visit www.gtcounty.org/mosquitocontrol.