The Ephemeroptera (Insecta) fauna of Yellowstone National Park consists of 46 species in 24 genera among eight families. These species are listed, and fifteen of the species (including collection data) are reported for the first time. Another 13 species have been taken adjacent to the park in Wyoming and Montana and noted as expected to occur in the park.
McCafferty, W. P. (2015). Mayflies (Insecta: Ephemeroptera) of Yellowstone National Park, U.S.A. Check List, 3(1), 4. https://doi.org/10.15560/3.1.4