Black Fly Spray Planned For Delaware River

The spray will take place Wednesday.

Provided by the Bucks County Department of Health:

A previous black fly spray in Pennsylvania. Credit: PA DEP

The Pennsylvania Department of Environmental Protection will be conducting an aerial black fly suppression operation on Wednesday, July 10, on the Delaware River from Slateford in Northampton County down river to the area near Trenton and Yardley Borough in Bucks County.

The operation will begin approximately 8 a.m. at Braden Air Park

The helicopter used for this operation will be light grey Bell 206L3, with red and blue stripes & tail number N660HA.

The aircraft is operated by Helicopter Applicators of Gettysburg.

Pennsylvania Department of Environmental Protection personnel will be on site at all landing zones managing the operation.

Helicopter Applicators Inc. will be dispersing Vectobac 12AS, which is a B.t.i. product manufactured by Valent Biosciences.  

B.t.i. is short for Bacillus thuringiensis var. israelensis, which is a bacterial larvicide, not a chemical, that kills the immature (larval) form of the black fly when they feed on it in the waterways.

Vectobac 12AS is a thick brown liquid resembling chocolate milk and is not toxic to fish, or other aquatic macroinvertebrates found in the treated waterways. The material is only applied to the surface of the water and not sprayed. 

This work does NOT involve a helicopter spraying over the entire county.

This work is targeted to portions of specifically mentioned waterways.

The helicopter will apply B.t.i. to the water at designated areas every few miles along the treated waterways.

Application is done by first circling the area to look for people on the ground or obstructions in the air. Then, the helicopter will fly perpendicular to the water flow (whenever possible) and apply the B.t.i. material, which is a brown, viscous liquid with a fish oil odor directly to the water.

For more information on the program please visit the Black Fly Program website.

SDS sheets and product labels are listed below.
Vectobac 12AS Label
Vectobac 12AS SDS Sheet

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