DEP Will Soon Begin Black Fly Spraying In 35 Counties

On April 18, the Department of Environmental Protection announced it will begin both aerial and backpack spraying on roughly 1,700 stream miles in 35 counties to control black flies.

The first aerial spraying, dependent on weather and stream flow, could take place on the Schuylkill River and several of its tributaries within the week. Other waterways will be treated as stream levels drop and weather conditions allow.

“As warmer weather returns, black flies are a pest that can inundate folks seeking outdoor recreation, especially around rivers and streams,” said DEP Secretary Patrick McDonnell. “Using environmentally compatible methods, this annual initiative reduces this nuisance so that Pennsylvanians can enjoy our natural resources.”

This year, 48 rivers and streams spanning more than 1,700 miles will be monitored and treated as needed. Spraying activities will be performed both by helicopter and ground crews. The frequency will depend upon weather and biological conditions.

Treatments cannot occur during periods of heavy rain or when water levels are high as these conditions lower the effectiveness of the treatment as well as significantly increase the cost of the control operations.

DEP uses Bti, a naturally occurring bacterium, to treat 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 notifies county and local emergency management officials prior to any spraying activity. Helicopters can be seen flying over waterways and ground crews using backpack sprayers off bridges and wading in streams conducting control operations on behalf of DEP’s Black Fly Suppression Program.

Anyone concerned at the sight of a helicopter or ground personnel 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.

Click Here for a list of participating counties and streams and rivers to be sprayed.

For more information, visit DEP’s Black Fly webpage.