An aerial black fly suppression operation has been scheduled for Wednesday May 14th on the main stem of the Susquehanna River, the Juniata River, Conewago Creek, Conodoguinet Creek, Sherman Creek and Penns Creek. This operation will begin at 0700 in York County and move north throughout the day. Flights will be conducted in York, Cumberland, Dauphin, Perry, Juniata, Mifflin, Huntingdon, Snyder, Union, and Northumberland Counties.