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    Field Operations

    The Pennsylvania Black Fly Suppression is based on field monitoring and laboratory identifications of black fly populations throughout the Commonwealth. The information gathered as a result of these processes is used by DEP biologists to schedule treatment operations, in coordination with aerial application contractors. DEP biologists are also responsible for reviewing treatment effectiveness.

    Black Fly Larvae Use Fans to Filter Feed Black Fly Larvae Use Fans to Filter Feed
    Sampling for Black Flies in a Stream Sampling for Black Flies in a Stream

    Larval/Pupal Sampling

    • Prespray samples help determine the need for and timing
      of treatments
    • 15-minute sample taken from riffle/run black fly habitat areas
    • Sample vegetation, debris and rocks, with fingers and forceps
    • Transfer larvae/pupae to vials of 70% ethanol for Lab Identification
    • Postspray Samples help determine treatment effectiveness

    Adult Sampling

    • Sampling sites established at parks, schools, ballfields, & other outdoor recreation areas.
    • Disturb vegetation for 100 meters, lay down trail of CO 2 and human scent
    • Take 9 sweeps (3 sets of 3 sweeps) with 10 in. net, shake down adults
    • Transfer adults to labeled sample bottle of 70% ethanol for Lab Identification
    • Collectors are prohibited from smoking or using tobacco products, and may not apply insect repellents during the collection process
    Adult Sampling
    Lab Identification of Black Flies Lab Identification of Black Flies

    Laboratory Identification

    • Samples delivered to PA DEP Laboratory for identification
    • DEP biologists and interns identify samples using microscopes and taxonomic keys
    • Species identifications and counts, as well as life stages, are recorded in GIS-based data system
    • This information is used in planning and reviewing statewide black fly treatments

    Spray Operations

    • Treatments scheduled only when larval sample results indicate presence of human pest species (i.e.Simulium jenningsi )
    • DEP notifies federal, state, and county authorities, including emergency management personnel, of upcoming black fly treatments
    • DEP biologists direct treatments in coordination with aerial application contractors
    • Treatments consist of aerial applications of environmentally-safe, naturally-occurring soil bacteria, Bti
    • Reviews of treatment-effectiveness after each treatment are conducted by DEP biologists
    Helicopter Spraying to Control Black Fly Populations Helicopter Spraying to Control Black Fly Populations
    Non-Target Biomonitoring Non-Target Biomonitoring

    Non-Target Biomonitoring

    • Bio-monitoring of aquatic macroinvertebrates and fish is conducted by DEP on selected treatment streams to ensure there are no environmental impacts
    • Samples collected using US-EPA Rapid Bio-Assessment Protocols at Bti-treatment sites and compared to samples from untreated control sites.
    • Data analyzed using metrics for species richness, diversity, abundance, population density, composition and tolerance
    • Results confirm that a carefully managed Bti treatment program can provide effective black fly control with no major impacts to non-target organisms
    • A DEP-funded five-year study by the Academy of Natural Sciences of Philadelphia and Stroud Water Research Center found no significant impacts to fish and insects