Summer might be over, but one warm-weather pest refuses to leave.
Recent rains and high tides have combined to create a fertile breeding ground for mosquitoes in Beaufort County.
The county's Mosquito Control Office has received 216 calls for service so far this month, mostly in northern Beaufort County between Burton and Yemassee. That compares to 40 calls in September.
"We are seeing a huge emergence of salt-marsh mosquitoes," said the office's director, Gregg Hunt.
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Meanwhile, rain and winds have grounded efforts to spray insecticides.
The office has sprayed an average of three mornings per week using one airplane and five trucks. It would spray more often, but pilots and drivers need calm air, Hunt said.
"We need temps of at least 50 degrees and winds up to no more than 10 mph and no rain," he said. "We can't send our trucks or planes out because then the product won't reach the target zone and may go farther than intended. The application becomes less effective."
Another challenge: Most mosquitoes lay their eggs in environmentally sensitive salt marshes, which mosquito-control trucks and aircraft avoid.
The EPA-approved insecticide has a kill rate of up to 95 percent, Hunt said, but with millions of adult mosquitoes emerging each day, those killed are soon replaced.
So far, mosquito activity has not been as bad this year as last year, but another wave is on the way.
"We have the highest tide of the year during the last week of October, which means we'll have another wave of salt-marsh mosquitoes pestering residents by mid-November," Hunt said. "It takes about 14 days to develop from an egg to the adult state. We're not through the mosquito season yet."
Last year, the office received 1,064 complaints. It has received 716 complaints so far this year. Hunt said 2010 was the worst in years.
Beaufort County has not recorded a positive test of West Nile virus this year, Hunt said, while nearby Chatham County, Ga., has discovered the virus in 213 mosquito samples and one human. Four more people are suspected of carrying West Nile, and another is presumed to have contracted the virus based on donated blood that was tested, said Dr. Henry Lewandowski, Chatham County mosquito-control director. No one has died from the virus locally, he said.
There was one positive test of West Nile in mosquito samples taken in Jasper County. Three mosquito samples tested positive in Columbia and one in Orangeburg, said entomologist Chris Evans with the S.C. Department of Health and Environmental Control's Bureau of Laboratories.
Until a hard freeze, people should take precautions when staying outside after dark and watch out for dead birds, Evans said.
"Mosquitoes become infected with the virus when they feed on infected birds. They then transmit the virus, during feeding, to humans and animals," he said.
Follow reporter Tom Barton at twitter.com/EyeOnHiltonHead