Georgia’s rainfall deficit has caused a mosquito population explosion that has led to a rise in the number of West Nile virus cases reported in the state.

The virus is carried by the southern house mosquito, which breeds in storm drains and thrives in polluted water, said Elmer Gray, an entomologist with the University of Georgia College of Agricultural and Environmental Sciences.

Mosquitoes are vectors of the virus, but birds are carriers. The mosquitoes become infected when they feed on infected birds. Infected mosquitoes then transmit the virus to humans through their bites.

Last year, nine cases of West Nile virus were reported in Georgia, he said. So far, more than 25 cases have been confirmed this year. And Gray is confident this number will keep rising.

"We haven’t had much heavy rain this summer to flush out the storm drains (and wash away the mosquito larvae)," Gray said. "If we’d been hit by hurricanes and heavy rains, the storm drains would be flushed out, but buckets and tires would be full for the Asian tiger mosquitoes to breed in."

Asian tiger mosquitoes are what Gray refers to as "nuisance" mosquitoes, but they are not vectors of the virus. They show up at backyard picnics and other social gatherings. This mosquito breeds in standing water found in old tires, buckets or anything that will hold rainwater.

"These mosquitoes are found in urban areas such as Atlanta and Athens," he said. "If you live on the coast or your property backs up to a swamp, you could have one of several species."

Gray’s colleague Nancy Hinkle, also a UGA entomologist, says homeowners have actually helped Asian tiger mosquitoes overcome the lack of rainfall.

"Because people have irrigated their lawns more, water-holding vessels such as flowerpots, buckets and cans around homes have been regularly collecting water," Hinkle said. "People recognize the value of every drop of rain, and more and more people have fashioned rain-collection devices."

Storing rainwater to use to irrigate outdoor plants is wise. But it creates perfect backyard mosquito habitats, she said. To avoid such problems, use a mosquito larvicide containing B.T. such as "mosquito dunks."

If he had a choice, Gray would choose to see heavy rainfall and high populations of Asian tiger mosquitoes.

"I’ll take a few bites over an illness any day," he said. "Mosquito-vectored diseases can be a really serious health problem for you and your family."

Ticks and fleas don’t seem to mind droughts.

"Ticks are hardy, and their leathery skin and water-conserving behaviors protect them from the ill effects of drought," Hinkle said. "And because fleas are so well-adapted and so dependent on their host, they aren’t usually affected, either."

Thanks to Sharon Omahen, UGA CAES news editor.