Aerial Spraying for Black Flies

The Pennsylvania Department of Environmental Protection (DEP) will conduct an aerial black fly suppression operation at the Washington Crossing State Park at 8:00 a.m. on Tuesday, June 18, 2024.

The Delaware River will be treated from the Trenton, NJ area to Slateford in Bucks and Northampton Counties. The Lehigh River will be treated from the Delaware River upstream to the Walnutport area in Lehigh.  

The helicopter used for this operation will be a Bell UH1H "Huey" with tail number N638HA and is painted blue with white stripes (this is a larger and louder helicopter). The aircraft is operated by Helicopter Applicators of Gettysburg, PA. DEP personnel will be on-site at all landing zones, managing the operation.

Vectobac 12AS is B.t.i. product manufactured by Valent Biosciences. The B.t.i. material is a naturally occurring bacteria (Bacillus thuringiensis israelensis) that kills the immature (larval) form of the black fly when they feed on it in the waterways. It is a bacterial larvicide, not a chemical, and is the only product used in Pennsylvania's waterways for black fly suppression. B.t.i. is not toxic to fish or other aquatic macroinvertebrates found in the treated waterways, degrading quickly in the environment.

Black flies, also known as biting gnats, are considered a pest that can inundate people seeking outdoor recreation in the warmer months, especially around rivers and streams. 

For more information on the program, please visit the Black Fly Program website: Black Fly (pa.gov).

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