Rain Swells Mosquito Numbers

Population At Two-decade High, Money For Control Efforts Dwindles - And There Are Still Seven Weeks In The Season

August 22, 2009|By Sarah Fisher | Sarah Fisher,sarah.fisher@baltsun.com

Maryland's mosquito population has reached what some are calling a two-decade high, while funding to fight the disease-carrying pest is dwindling, according to state officials who say they fear they will run out of money before mosquito season ends.

"We've had a very active year," said Mike Cantwell, program manager of the Maryland Department of Agriculture's mosquito control division. "We are getting close to our budgeted amount for many counties and we still have seven weeks to go."

After an abnormally rainy spring fostered large mosquito populations, the division used up much of its budget to combat the swarms, he said. Now, with hurricane season looming and the promise of more rainy conditions that are ideal for mosquito breeding, aerial and ground insecticide spraying efforts are in jeopardy.

The state has sprayed insecticides by plane over 268,000 acres so far this year, Cantwell said. In a typical mosquito season, which lasts through October, it sprays 300,000 acres, putting the division well ahead of its normal spraying schedule.

Despite a relatively dry July, some are calling this the worst mosquito season in 20 years, said David Schofield, assistant program manager of the mosquito control division.

His office oversees mosquito control on the Eastern Shore and uses a "human bait" technique to count the winged pests. Two people stand outside and count the number of mosquitoes that land on their arms and legs in two minutes. Aerial spraying is in order if the count reaches 12 mosquitoes per minute.

"Southern Dorchester County has been experiencing landing rate counts exceeding 100 per minute," Schofield said. "Those are horrendous numbers. Normally in the summer you don't break double digits for one minute."

Tony DeWitt, an agricultural inspector monitoring Baltimore and Harford counties, said numbers have remained high in residential areas there as well. Even areas typically not infested have been invaded, he said.

The mosquito control program, which is voluntary, requires local jurisdictions to contribute funds to participate. Baltimore City does not participate in the state's program because it does not provide the required funds, Cantwell said.

The Baltimore City Health Department responds to complaints about mosquitoes by emptying containers with standing water or treating standing water with chemicals to kill mosquito larvae, said Juan Gutierrez, assistant commissioner for environmental health. So far this year there have been 99 mosquito-related investigations, compared to 199 in 2008, he said.

Jeannine Dorothy, a state entomologist whose College Park office oversees the mosquito control program in nine western and central Maryland counties, including Baltimore, said budget cuts have had an impact on this year's efforts. The program is operating without four of the seasonal employees who administer the insecticides, she said.

"We just have to work to the level of the budget," Dorothy said. "When we come to the end of the money, we stop."

The state's total budget for the mosquito control division is $2.9 million, with $1.7 million from the state's general funds and $1.2 million generated through fees from the counties.

With more rain likely through the weekend, more mosquitoes are also likely, adding to an already rising population.

The most active part of the hurricane season begins in mid-August and lasts through late October, according to the National Weather Service.

Because mosquitoes can transmit diseases such as the West Nile virus, they are more than just a nuisance.

According to Schofield, five mosquito pools in Maryland have tested positive for West Nile, four in Worcester County and one in Prince George's County. No cases of human transmittal of the virus have been reported in Maryland this summer.

But with the mosquito season's two busiest months coming up, Schofield said, "We're nervous on our end."

The buzz on Maryland mosquito control

* 268,000 acres sprayed by air so far this year

* $2.9 million total spent in mosquito control, $1.7 million from the state's general fund and $1.2 million from local fees

* 7 weeks remaining in mosquito season

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