Flatheaded mayfly nymph

The small, brown Flatheaded mayfly nymph (Heptageniidae), sometimes called the “crabwalker mayfly”, has a flattened head that helps it live in fast-flowing waters. A nymph is an immature insect that lives in water, looks like the adult of its species only smaller, and grows through multiple stages of molting. During the nymph stage of its life, the mayfly is a favored food for fish in the Bay Area including bluegills and brown trout. Did you know the mayfly was placed in the same ancient insect group as dragonflies?