Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
Allen, R.K., and Edmunds, George F. Jr. 1963. A Revision of the Genus Ephemerella (Ephemeroptera: Ephemerellidae) VII. The Subgenus Eurylophella. Canadian Entomologist 95: 597-623.