MARTIN COUNTY, Fla. -- Mosquito control workers on the Treasure Coast are fighting this year's first broods of salt marsh mosquitoes by flooding marshes along the Indian River Lagoon to spoil breeding conditions for the biting pests and spraying places where they have gained a foothold.
"We're at the cusp of the mosquito season," said Gene Lemire, director of Martin County Mosquito Control.
Workers began spraying hot spots for mosquitoes last week, he said. Truck spraying for adult mosquitoes began this week and will continue throughout the season, which generally ends in November.
The benefits for controlling mosquitoes include a greatly reduced threat from mosquito-borne disease, and an overall improvement in the quality of life, Lemire said.
Experts said the summer of the 2011 season was one of the worst for mosquitoes in recent years. Although there's no telling yet what to expect this year, preparing for a similar season is key.
"We had just the right amount of rainfall to make (2011) a bad summer," said Doug Carlson, director of the Indian River Mosquito Control District in Vero Beach.
Rainfall will dictate whether Treasure Coast residents will have to swat and spray themselves as much as they did last year. But Carlson said experts can't provide a precise expectation.
Officials in the three-county area said last week's rain — up to 2 inches in some locations — wasn't enough to start hatching broods of freshwater mosquitoes. But high spring tides along the coast started hatching salt marsh mosquitoes early this year.
"We had a very tough spring spraying for tidal marsh mosquitoes," said Jim David, director of St. Lucie County Mosquito Control. "We used every man and piece of equipment we had on them, and I think we're finally winning."
Thousands of acres of Indian River Lagoon salt marshes surrounded by man-made dikes have been pumped full of water in all three counties starting on April. While many types of mosquitoes lay their eggs in water, salt marsh mosquitoes need moist soil on which to lay their eggs, which hatch when high tides or heavy rains flood those low-lying areas. Keeping the marshes flooded from spring until fall foils their reproductive strategy.
The severity of mosquitoes is often judged by landing rates — literally, how many mosquitoes bite a mosquito control worker in one minute.
So far this spring, landing rates have topped out at a severe 20-plus deep in some marshes on the northern Treasure Coast.
"Luckily, they haven't made it into the neighborhoods yet in such large numbers, Carlson said. Trouble spots this spring have centered around Indian River's south barrier island and the southwestern shore of the mainland, he said.
There hasn't been enough rain this spring to start freshwater mosquito breeding.
"But that will be coming along soon," Carlson said.
So far this spring, Martin County seems to have had the least mosquito problems on the Treasure Coast. An isolated spot in Jensen Beach needed to be sprayed by hand last week when landing rates started to hit about a dozen per minute, Lemire said.
"Over the past two months, it's been dry," he added. "People are used to having no mosquitoes. Then they get one or two and it seems bad."
Spraying to kill mosquitoes and the seasonal flooding of salt marshes in the Indian River Lagoon managed to do the most harm to mosquitoes while having the least negative impact on nature.
"We have to balance what we do with environmental concerns," Lemire said. "We don't eliminate mosquitoes. We control them.
"It's Florida," he added. "It's hot and buggy. You're going to see a few mosquitoes."
Staff writer Lamaur Stancil contributed to this report.