• Hunterdon Board of Commissioners

Hunterdon, State, and PADEP Join Together To Fight Black Flies

Updated: Jul 20, 2021



The Pennsylvania Department of Environmental Protection (PADEP) conducted the first black fly suppression via helicopter spraying on both sides of the Delaware River on April 21st, Hunterdon County Commissioner John E. Lanza reported at the Board’s May 4th meeting.

Lanza stated, “I can report that the Pennsylvania DEP conducted the first black fly suppression spraying for 2021 on both sides of the Delaware in Hunterdon County on April 21st. We appreciate that New Jersey is again sharing the cost with Pennsylvania in support of the spraying operation that is conducted by helicopter over the river.

Black flies are a nuisance not only to residents seeking to enjoy their decks and patios or other outdoor activities, they also have a negative effect on outdoor tourism enterprises, which are so very important to Hunterdon County’s economy, and have become even more important during the pandemic.”


Lanza said, “You may recall that in 2019, the NJ DEP had not provided funding to the PADEP for New Jersey’s share of the suppression activities. At that time, this Board authorized a payment to the PADEP in support of aerial spraying along the Hunterdon County portion of the Delaware, in order to grant some relief to our residents.

The application usually covers the Delaware River from Trenton north to Warren County, so it is truly a state responsibility. The spraying is anticipated to be conducted several times over the next few months. It is refreshing to be able to report positive actions by the state in this regard.”


According to the PADEP, a bacterial larvicide, not a chemical, is dispersed. The material eliminates black fly larvae in the river and is not harmful to aquatic life or people.

Lanza added “Hunterdon County Vector Control Division Head Tadhgh Rainey has reported that the Division also conducts spraying, using the same material, along the South Branch from Clinton to Three Bridges, several times during the summer into the fall.”

More information on the larvicide material used can be found on the County Vector Control Division’s, Hunterdon County Health Services.

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