The male is called the “Chocolate Dun” and the female is called the “Olive Sulphur”. These mayflies are also called the “Little Dark Hendricksons”. They are most abundant in streams with lots of vegetation. The most abundant species is the Ephemerella needami. We think the duns are close enough that one pattern will work for it. However, the male and female spinners of this species look very different. The females have a very rusty appearance and for that reason we have two patterns for the spinners.