Common Mayfly

Ephemera vulgata is a representative European mayfly, one of about 3,000 species in the order Ephemeroptera. Mayflies have what is arguably the most extreme life history of any insect: aquatic nymphs (called naiads) live in streams and lakes for 1-3 YEARS, breathing through external gills, eating algae and detritus. Then, on a single specific evening of the year, the entire local population synchronously emerges, transforms into a winged adult on the water surface, and lives for at most 24 hours — and often as little as 5-10 minutes. Adults have no functional mouthparts and cannot eat. Their entire adult existence is dedicated to reproduction: a frantic mating swarm above the water surface, followed by the female depositing eggs and dying. Mass emergences in major rivers (Mississippi, Danube, Tisza) are so dense they show up on weather radar — the 'mayfly bloom' on Tisza River shrimp graphs has been recorded by hydrologists since the 1990s. Mayflies are taxonomically remarkable for being the only insects that molt AGAIN after gaining wings (the 'subimago' to 'imago' molt) — every other winged insect in history molts only at the wingless stages.