Insects · Ephemeroptera · Baetidae

Large Dark Olive Mayfly

Baetis rhodani

Not Evaluated

It has not yet been assessed against the IUCN criteria. See full glossary

A small and very abundant mayfly of European rivers, with three long tail filaments and transparent wings. Its streamlined, agile nymphs cling to stones in the rapids scraping algae, and the adults fly for barely one or two days.

Diet

Herbivore

Feeds mainly on plants.

Social structure

Solitary

Lives and hunts alone, joining others only to breed.

Sighting difficulty

Unknown

FreshwaterHerbivore Solitary Insect Freshwater

40countries

Fun facts

Mayflies are the only group of insects that moult after having wings: it emerges from the water as a subimago, a dull, matt winged stage, and a few hours later moults again to become the definitive adult.
The adult has no functional mouthparts and no working gut: it lives only to breed and dies the same day.
Its abundance is a classic indicator of water quality, and the biotic indices used to assess European rivers rest in good part on mayflies like this one.
Unlike most European mayflies, which have only one generation a year, it produces a second generation in the same season.
Its nymphs go on taking up oxygen normally even with their gills removed, which is not the case in burrowing mayflies such as Ephemera.
It is one of the key species in the biological water-quality indices used on European rivers.