Derived from the classic Trout Stream Insects: An Orvis Streamside Guide, this fully revised text focuses exclusively on those mayfly species of most importance to fly fishers. The numerous color photographs, drawings, and insect-size silhouettes help the angler identify what's hatching and compare that natural insect to what's in the fly box. Designed to slip easily into a jacket or vest pocket, the trout angler will make much use of this book.