In the delayed harvest streams and the large stocked streams, there are some large rainbows feeding on the natural midges. The Bridge Pool on Back Creek (see page 65 of my Virginia Blue Ribbon Stream book) and the flat above the bridge on Passage Creek are both great spots.
If you see a delicate dimple riseform, the trout is taking an adult midge from the surface and will often take a Mr. Rapidan Midge Dry size 18.
If you see a splashy riseform or a swirl at the surface, he is taking an emerging midge headed for the surface.
The Mr. Rapidan Olive Soft Hackle size 16 will take many of these trout fished just below the surface with a slow lifting action.