Aquatic insects are one of the trout's primary diets. From the early nymph stage of development through hatching on the surface, trout feed on flies. Here in the early spring, the wet fly fisherman can be very successful. At certain times of the day, the Blue Duns, Blue-winged Olives and Quill Gordons are hatching. These May flies must be fished slow and deep, drifting freely and naturally in the current.
Some fly fishermen prefer to use nymphs.
You might try a Montana nymph, which is black with a yellow thorax and represents a black stone fly. The nymph fisherman drifts his fly along the bottom, bouncing it off the rocks. At the slightest hesitation, he sets the hook. This early fishing is very selective and extremely delicate. The fish don't hit as aggressively as they do later in the season.