The Little Yellow Stonefly is one of our longest lasting hatches, going for two months in some streams. This means there are great numbers of nymphs in the streams for a long period. A good way to take advantage of this is to fish the Murray's Little Yellow Stonefly Dry size 16 on a Classic 7.5ft 6X leader with a Murray's Little Yellow Stonefly Nymph size 16 as a dropper below the dry.
Other flies you should have in your fly box for the native brook trout streams include the Murray's Flying Beetle size 16 and Mr. Rapidan Ant size 16. There are many beetles and ants along the streams and these flies seldom let me know.
The Shenandoah National Park streams are holding up surprising well for this time of year. The streams levels are good but still be careful on your approach so that you are not spooking the fish. If you need help on finding access to the Park streams, see my book Trout Fishing in the Shenandoah National Park or download my digital video.