Testing by the Department of Environmental Protection for the Black Fly Aerial Spray Program began Tuesday in Warren County and spraying could start as early as Friday.
Spraying will take place in Warren County along the Allegheny River, Brokenstraw Creek, and Conewango Creek, and DEP Press Aide Amanda Whitman said the first scheduled spraying is dependent on Tuesday's results.
The DEP sprays BTI, "a naturally occurring bacterium, to target the larval stage of four specific human pest black fly species" that "degrades quickly in the environment and does not harm the aquatic ecosystem, fish, birds or other insects."
Statewide spraying will continue through August and cover 44 rivers and streams, and 1,500 miles in 33 counties.
"This effort greatly reduces the black fly population, making it easier for Pennsylvanians to enjoy outdoor activities during warmer months," according to the DEP.
The spraying will be done by helicopter with frequency dependent on testing results and weather conditions. Spraying is ineffective during heavy rain or when high water levels and and fast-moving water can carry the spray away, according to DEP.
DEP will contact local emergency management officials before the spraying begins to inform them that the helicopters are part of the state program. Residents with concerns over the sight of a helicopter are encouraged to call the emergency management office to verify that a black fly treatment is taking place in their area on that day.