The Prince nymph is a popular fly for both rivers and lakes. It is a general searching pattern, resembling nothing in particular, but many things in general. The larger sizes can be used as imitations of the smaller stonefly species.
A bead head is optional, but is usually a good idea. The traditional tie uses brown hackle, but CDC can be an effective substitute.
How to Fish
In rivers, dead drift the fly near the bottom with the indicator or tight line presentations. In lakes, use an intermeditate line and a count-down-and-retrieve or slow retrieve presentations. When lake fishing, experiment with different retrieves until you find one that works well: slow and steady, slow pulls with a pause between pulls, short pulls of moderate speed.