A review of the literature indicates that Stenonema vicarium (Walker) adults have not been collected from northeastern Minnesota. However, mayfly nymphs which key to that species, based on the descriptions in Lewis (1974), have been collected from many streams in the area which are also inhabited by nymphs of the closely related species, Stenonema fuscum (Clemens).
Lager, Thomas M. and Lewis, Philip A.
"Notes on Mayfly Nymphs from Northeastern Minnesota Which Key to Stenonema Vicarium (Ephemeroptera: Heptageniidae),"
The Great Lakes Entomologist: Vol. 11
, Article 7.
Available at: http://scholar.valpo.edu/tgle/vol11/iss4/7