Degree-day-development
Guides
Caenis
Common Square-gills
Caenis is a genus of small mayflies in the family Caenidae, commonly known as "square-gilled mayflies." Adults are among the smallest mayflies, with some species measuring only 3–4 mm in body length. The genus is globally distributed across multiple continents and serves as an indicator taxon for aquatic ecosystem health. Nymphs inhabit various freshwater environments, and adults emerge in synchronized events.