Heptageniidae are one of the most abundant and widespread components of Wisconsin's aquatic insect fauna. In almost any stream with a firm substrate and free of gross pollution, the flattened nymphs can be found hiding in crevasses and under rocks, or clinging to submerged wood. Adults and nymphs are easily distinguished from mayflies of other families, nymphs by their dorsoventrally flattened head and dorsal eyes, and adults by their 5-segmented tarsi and complete wing veination. This paper presents our knowledge to date of Heptageniidae in Wisconsin.
Flowers, R. Wills and Hilsenhoff, William L.
"Heptageniidae (Ephemeroptera) of Wisconsin,"
The Great Lakes Entomologist, vol 8
Available at: https://scholar.valpo.edu/tgle/vol8/iss4/5