Without the familiar pitter-patter of summer rain, some of Tampa Bay's back yards have grown abuzz with another — and unlikely — killjoy: the mosquito.
Though the abnormally dry conditions of late have sapped many mosquitoes of their natural incubators, the peskiest and most opportunistic of the insect species have nonetheless taken advantage of Tampa Bay's moist coastal lowlands.
Since June 1, Pinellas County Mosquito Control has fielded 215 service requests, more than doubling the 78 requests it received during the same span last year, said its operations manager, Nancy Iannotti.
That steep uptick runs in contrast to a recent dip in the area's overall mosquito population, but parallels a boom in salt marsh mosquitoes, a breed known for its persistence — and its bite.
Meanwhile, Iannotti said the domestic mosquito — commonly known as the "ankle biter" — has weathered the dry conditions by relying on leftover water in clogged roof gutters and in unattended pools behind foreclosed homes, among other places.
Iannotti said the volume of requests has as much to do with the nature of the salt marsh mosquito as it does the population spike.
"They're horrible biters," Iannotti said. "There are a lot of people living near salt marsh areas. Coastlines are prime locations for homes. When they come off, they're in such huge numbers and they're such bad biters. And they can be out in any time of the day, while others generally will be out only at night."
From beaches in Fort De Soto to Honeymoon Island State Park, where their larvae usually lie just beyond water's reach, the vociferous salt marsh mosquitoes proliferated with the help of unusually high tides with high temperatures.
"The mosquito lays drought-resistant eggs, which don't hatch until the marsh is flooded," said Jonathan Day, a medical entomology professor at the University of Florida, who has observed a similar paradox across the state in Vero Beach. "Even though we have a real drought situation, marshes can get flooded by unusually high tides."
Tampa Bay is vulnerable to becoming a mosquito breeding ground as the wetter weather arrives, because the spring's heavy rains raised the water table to a point where it could swell and form pools of standing water for accumulated larvae to hatch.
A concerted "larvicide" effort has helped reduce service calls and the overall mosquito population in Pasco, said Dennis Moore, director of the county's mosquito control district. But with summer rains on the way, his office is bracing for busier days.
"As soon as these rains pick up, we'll have a big challenge in front of us," he said. "There are a lot of eggs out there ready to hatch."
Although salt marsh mosquitoes aren't responsible for spreading diseases, other mosquitoes can pose public health risks during dry-weather conditions, experts said. With fewer water holes to choose from, mosquitoes and their primary source of nourishment — birds — tend to congregate, creating a concentration that has proven to increase and accelerate the spread of West Nile Virus, Eastern equine encephalitis and other mosquito-borne diseases.
"The possibility for them to be at the same waterhole is much higher," said Dr. Carlos Fernandes, director of the Hillsborough County Mosquito Control. "Sometimes the population goes down but the level of disease, the level of contamination of mosquitoes, tends to go up.
"It's kind of a funny thing we observe."
From the beginning of February to the end of May, Fernandes said Hillsborough County's mosquito control collected a monthly average of about 60,000 mosquitoes — almost twice that of the same span last year. That average coincided with about 100 service requests per day, he said. But with the dry weather, the daily average for service requests has sunk to between 30 and 50 a day.
He said mosquitoes from the genus culex, a type similar to salt marsh and domestic breeds, have proven surprisingly prevalent this month. They've been known to carry West Nile virus, St. Louis encephalitis and heart worm, he said.
In July 2005, a 27-year-old man became the first West Nile virus case in Pinellas County. The number of cases reached double-digits in an outbreak officials suspect was influenced by the dry weather. Later that summer, an 18-month-old Land O'Lakes girl died of Eastern equine encephalitis, a disease that reappeared this month in a chicken held at a Hernando testing facility.
From April 1 to June 15 of that year, total average rainfall for Pasco, Hillsborough and Pinellas Counties was 13.67 inches, according to the Southwest Florida Water Management District. In the same span this year, total average rainfall was 4.26 inches.
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