Fly fishing flies that imitate insects that trout and other game fish feed on are perhaps the most diverse and interesting category of fishing flies. For centuries anglers have been observing the most obvious form of trout behavior: The rise to hatching insects. For much of that time, little thought was given to the less obvious but much more important activity below the water’s surface. Even today, when we know that to be more successful we should be fishing more nymphs and emergers, it is hard for us to turn away from the fascination of watching a trout rise to our fraudulent surface offerings. Is it any wonder that there are hundreds more dry fly patterns than all of the other types put together? That has been changing steadily in recent years as anglers devote more time and ingenuity to subsurface patterns.