The trout are gorging themselves on the great numbers of natural black ants found along our trout streams. Many are dropping from tree limbs that hang over the streams or tumbling into the streams from boulders and brush along edges. Since the natural ants react differently in various parts of the streams, I try to mimic this natural fly-action with my fly. Sometimes using a dead drift, or a splat presentation or a twitch action. The Mr. Rapidan Ant size 16 works well and the yellow calf tail material on it helps me see the fly on the water. Fish these on a Classic 6X leader and don't forget your dry fly floatant.
Some of the native brook trout streams are low and the trout are wary. Other streams are carrying extra water on the lower boundaries from the heavy rain storms that went through some areas but not others. I think you will do best by coming into the streams from the Skyline Drive or headwaters and hiking down 45 minutes and then fish back up. Be sure to not walk along the stream as you are hiking or get behind someone else as the trout will already be spooked.
My book Trout Fishing in the Shenandoah National Park covers the access to the Park streams. I recommend carrying the book and the maps (Map 9, 10, 11) with you as you are exploring the streams. We will be conducting our Mountain Trout Schools starting again in late March 2021 through mid May. See the 2021 schedule.