Little Yellow Stonefly or Yellow Sally - Insect Genus Isoperla
This group of stoneflies includes over 60 species, which are quite common to many well oxygenated, fast flowing, gravelly bottomed rivers across the U.S., hatching sporadically from May through much of the summer.
Nymph: Nymphs often grow up under rocks in swift riffle and run portions of the river, dining on smaller bugs that inhabit those rocks. Before the yellow sally nymph hatches, they crawl toward shore where the water is calmer. During this trip, they often get dislodged, drift down river, and become a tasty meal for trout. Try a dead drifted little sally nymph through riffles and runs on these rivers. As the hatch progresses, target the edges of the river with the same dead drifted nymph.
Adult Yellow Sally Stonefly: Nymphs crawl onto dry land late in the afternoon, evening and night, where they break out of their exoskeleton to become a flying adult. After mating, the adult female returns to the water to lay eggs, then she dies. Watch for these bugs flying around overhanging bushes, cast a dry Sally in the same area, and the fun begins! These rises are often acrobatic and splashy! Once the Sally dies, you can imitate this with a dead drifted dry sally.