The Pennsylvania Department of Environmental Protection has begun aerial spraying on streams across Pennsylvania to control black flies, also referred to as gnats.
Pennsylvania rivers and streams will be monitored and treated as needed. Spraying activities will be performed both by helicopter and ground crews; their frequency will depend upon weather and biological conditions. Treatments cannot occur during periods of heavy rain or when water levels are high as high water conditions lower the effectiveness of the treatment.
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.
Two waterways in Bucks County are part of the spraying program — fhe Delaware River and the Tohickon Creek.