Seeking to calm people angered by a plague of flies, the Carroll County Health Department this week sent a letter to Bachmans Valley residents, detailing the county's investigation of the insect swarms.
It acknowledges that officials have been unable to find a solution.
Dozens of residents last month said the flies in the valley had made them prisoners in their homes, and 42 signed a petition asking local officials to do something about the swarms. Some homeowners, who had seen white outdoor surfaces turn black with fly droppings at the heigh of the swarming last month, said they were considering moving away.
For them, the county's letter offers little hope. The Health Department writes that it has "limited power" to deal with the flies because of its relative inexperience with such problems and because state law limits the fines it can assess against the chicken farms that are being blamed for creating the crisis.
"A safe, effective method of eliminating the existing adult flies from the area has not been found," the letter says.
Larry L. Leitch, the county's deputy health officer, said yesterday that the letter, labeled the "Bachman Valley Fly Problem Information Sheet," was mailed to about 25 residents who have called the health department to complain.
"Although this has to be solved jointly with a number of groups, including the residents, we decided we would send out a letter letting people know some information," he said.
According to the letter, the Health Department's investigation found that manure spread on the property of two chicken farms -- County Fair Farms in the 600 block of Bachmans Valley Road and the Mullinix egg farm in the 500 block of Saw Mill Road -- had combined with the hot, humid weather to cause the swarms.
At County Fair, the letter blames an owner, Donald K. Lippy, for the fly problem. Mr. Lippy has acknowledged that he spread a small amount of untreated manure in the fields near Bachmans Valley Road.
But at the Mullinix farm, the letter blames the U.S. Department of Agriculture for having manure spread there while its scientists prepared the chicken houses for study.
"This occurred at the same time flies coming from the other operation's manure were laying eggs," the letter says. "The result was that the numbers of flies did not decrease as expected, but increased dramatically."
In an interview this month, Larry Pickens, a research entomologist for the USDA who has visited the site, disputed that. He said farmer George Mullinix spread the manure against the wishes of federal officials.
But county health officials said they are more concerned with reducing the flies than with fixing blame. The letter says the Health Department, working with the farms and state agriculture experts, is using insecticides and "biological controls" to fight the flies.
Mr. Lippy has said in previous interviews that he is changing the way his farm disposes of manure. The county's letter says the farm owner is willing to have residents visit County Fair to discuss the problem.
But residents said yesterday that Mr. Lippy's assurances and the county's letter do not satisfy them. Several homeowners said they will continue to hold meetings and seek remedies until local officials offer a solution.
"You see, that's what our whole complaint is -- that the county doesn't have a solution," said Cyndy Rosenbloom, a 35-year-old doctor's assistant who moved to the valley with her husband in March. "They have said they believe it'll eventually go away. But the flies are laying eggs, and they're not going away."
Joe Wood, who lives on John Owings Road within a mile of County Fair, said residents have discussed demanding a reduction in their property taxes if county and state government fail to deal with the flies. He said the community's frustration is growing as the pests prove to be persistent.
"Last week, it seemed like it had gotten a lot better," said Mr. Wood, who has been forced to cancel the annual picnic he usually holds for Carroll County's chapter of the American Wine Society because of the pests. "But [Tuesday] night and [yesterday], they were back in full swarm."