Busy mosquito season tapers off in dry July

Eastern Shore spray budgets tapped out

July 17, 2011|By Frank D. Roylance, The Baltimore Sun

Drought conditions on the Eastern Shore are taking a toll on farmers' crops, but the dry weather is having at least one beneficial effect — there are fewer mosquitoes.

After a busy start to the mosquito control season that put a deep hole in state and local aerial spraying budgets, mosquito populations have diminished, and the spraying has stopped.

"Thank God they've slowed down," said Mike Cantwell, mosquito control program manager at the Maryland Department of Agriculture. "We haven't done any aerial spraying since July 2nd, and we're hoping this pace will diminish. We can't keep up the pace we were in in May, June and early July."

By July 2, the state had done aerial spraying over 198,000 acres, just short of the 2009 record of just over 200,000 acres for the same period.

"We establish budgets with each of the Big Four counties — Worcester, Wicomico, Somerset and Dorchester — and this year we have spent the Dorchester County air spray budget, and slightly exceeded it," Cantwell said. More spraying will require more money from both the county and the state.

Dorchester County Manager Jane Baynard said she was briefed on the matter last week, and plans to bring it before the County Council at Tuesday's meeting.

"We have had a very heavy [mosquito] population," she said. "The state is estimating it's as bad as we've seen in our county for 20 years or more."

Despite what she described as "a difficult budget" this year, Baynard said, "I'm sure they [the council] will look at it very seriously."

Cantwell said, "The board … down there [in Dorchester] will have to decide whether the county can afford to cost-share with the state" for more spraying. "If the county can come up with their share, we can come up with our share."

Mosquitoes aren't just a nuisance. Some can transmit disease to humans and to animals.

West Nile virus, introduced in the United States in 1999, typically sickens 20 percent of the people who become infected. It causes serious, sometimes fatal illness in less than 1 percent. Mosquitoes in Maryland can also transmit several forms of encephalitis to people and horses, and heartworm in dogs.

State budget cutbacks have clipped $1.1 million from the statewide mosquito control budget since 2004, when the mosquito-borne West Nile virus first became a major concern. In 2008, the state increased the county share of the aerial spraying costs from 50 percent to 60 percent.

The state now provides $1.9 million for all mosquito control services, including the aerial program. Participating counties kick in about $900,000, Cantwell said.

"We're not reducing services at this point," he said. But when the budget was submitted, the agency did tell state budget managers that it was only sufficient to cover mosquito control activities "if mosquitoes are at lower-than-normal levels."

And the spraying season is far from over, Cantwell said. Typically, 50 percent of the state's aerial spraying is done in the last eight weeks of the mosquito season, during the peak of the hurricane season when coastal storms can flood woods and salt marshes.

Cantwell isn't sure what caused mosquito populations to surge this spring.

The fresh floodwater mosquitoes that lay their eggs in low spots in the woods have rarely been a serious problem. "We don't find them to be widespread or in high numbers," he said.

This year, however, "we found them in areas where we didn't expect to find them, earlier than we expect and in greater numbers in both Eastern and Western Shore counties. … We have no explanation for that."

Rainfall at BWI Marshall Airport was above average in March and April, but below average in May.

Mosquito inspectors this year also found early broods of salt-marsh mosquitoes, Cantwell said. "Usually it isn't as extensive as later in the season, and we don't see them in very high numbers in the spring."

However, he said, "throughout this spring, with every lunar cycle, we had unusually high tides. That led to flooding of the marshes and successive broods of salt-marsh mosquitoes."



Maryland weather blog: Frank Roylance on meteorology

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