HARRISBURG The Department of Environmental Protection will soon begin aerial spraying on more than 1,600 stream miles in 33 Pennsylvania counties, including along the Schuylkill River in Schuylkill County, to control black flies.

The first aerial spraying will take place May 10 along the Delaware River. Other waterways will be treated as current and weather conditions allow." Adult black flies, also known as gnats, can be a nuisance to millions of Pennsylvanians and our guests from other states who enjoy spending time outdoors during warm weather," DEP Secretary Mike Krancer said. "We will once again be taking aggressive action to control black fly populations as they begin to hatch, and will continue to treat our rivers, creeks and streams in an attempt to make time spent outdoors this spring and summer as enjoyable as possible."This year, 47 rivers and streams spanning more than 1,600 miles will be monitored and treated as needed. Spraying activities will be performed by helicopter and the frequency will depend upon weather conditions. Treatments cannot occur during periods of heavy rain or when water levels are high. Fast-moving water can carry away the spray product, making the treatment ineffective. DEP uses Bti, a naturally occurring bacterium, to target the larval stage of four specific human pest black fly species.This bacterium degrades quickly in the environment and does not harm the aquatic ecosystem, birds or other insects. DEP will notify county and local emergency management officials prior to any spraying activity to make them aware that helicopters seen flying over creeks, streams and rivers are working on behalf of the state's black fly program. Anyone concerned at the sight of a helicopter spraying is encouraged to call their county emergency management office to verify that a black fly treatment is taking place in their area on that day. For more information on Pennsylvania's Black Fly Suppression Program, visit

www.depweb.state.pa.us, keyword Black Fly.