CAMBRIA COUNTY, Pa. (WTAJ) — A large helicopter began releasing a bacterial larvicide to reduce adult black fly populations to tolerable levels on Wednesday.

From July 27 until July 29., PA State Rep. Jim Rigby announced that the Bell 205 helicopter will be dispersing Vectobac 12AS, a bacterial larvicide that resembles chocolate milk, near tree top levels at various predetermined positions on streams. The helicopter began treatment in an area that included the Conemaugh River in Johnstown.

The helicopter conducting the treatment has tail number N658HA and is painted grey with blue striping.

The treatment is part of the Department of Environmental Protection (DEP)’s Black Fly Suppression Program. The program involves monitoring and treating approximately 1,700 miles of 48 Pennsylvania rivers and streams, according to the DEP’s website.

Local participating counties in WTAJ’s viewing area include Cambria, Huntingdon, Clearfield and Elk.

Residents who have been experiencing an abundance of black flies can submit a complaint on the DEP’s website here.

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For more information on the program, visit the DEP’s “Black Fly” page on its website.