We compared the phenology of nymph development, food type, and habitat selection of two stream mayflies, Stenacron interpunctatum (Say) and Stenonema pulchellum (Walsh) in Big Darby Creek, Ohio. Both species, which grow principally from autumn through early spring, emerged from the stream throughout the summer. The nymphs consumed the same sizes and types of food particles from deposits on stones, mostly in the form of detritus. As a result of morphological and behavioral adaptations, S. pulchellum lived on stones in swift water whereas S. interpunctatum lived on stones in a slower current.
Lamp, William O. and Britt, N. Wilson
"Resource Partitioning by Two Species of Stream Mayflies (Ephemeroptera: Heptageniidae),"
The Great Lakes Entomologist, vol 14
Available at: https://scholar.valpo.edu/tgle/vol14/iss3/5