Ephemeroptera: Taxonomy of the mayflies, with a brief description and list of references, from Tree of Life.
Ephemeroptera: Introduction from John R. Meyer's Entomology class.
Ephemeroptera Galactica: Information on mayflies (Ephemeroptera) for scientists and the layman.
Gordon Ramel's Mayfly (Ephemeroptera) Page: An introduction to biology, classification, and ecology of mayflies, the Ephemeroptera.
Mayflies: Fact sheet on Hexagenia spp. from Ohio State University.
Mayflies of the United States: Information on hundreds of species, including distribution maps and county checklists.
Mayfly Central: Mayfly research and resources at Purdue.
Shadfly.com: Stories, pictures, and videos of the mass emergence of shadflies (also known as mayflies, dunes, and dayflies) in North Bay, Ontario, Canada.