Reside in running water (streams) and attain maximum diversity in warm running water
Most mayfly nymphs are collector-gatherers or scrapers (this is the method the insects use to obtain food).
Most mayflies in temperate regions spend most of their one-year life cycle as nymphs.
Depending on the weather and the species, adults live from one hour to several days.

Illustration courtesy of B.C. Kondratieff, Colorado State University.