Diel-drift
Guides
Ephemeroptera
mayflies, Canadian soldiers, shadflies, fishflies, up-winged flies
Mayflies (Ephemeroptera) represent the oldest known winged insects, with fossil evidence dating to approximately 350 million years ago in the lower Carboniferous. The order contains over 3,000 described species across more than 400 genera and 42 families worldwide. Adults are characterized by short lifespans—typically hours to days—and a unique subimaginal stage where the winged but sexually immature subimago undergoes a final molt to become a reproductive imago. Larvae are exclusively aquatic and serve as important indicators of water quality in freshwater ecosystems.