Doug Wechsler / Giant mayfly (Hexagenia) Adirondack Park, New York, USA, July.

Adrian Davies / Mayfly (Ephemera danica) on nettle, Surrey, England, UK, May.

Jussi Murtosaari / Brown Mayfly (Ephemera vulgata) adult male, Joutsa (formerly Leivonmaki), Finland, July.

Nick Upton / Green drake mayfly (Ephemera danica), newly emerged on a riverside grass stem, Wiltshire, UK, May.

Andy Sands / Mayfly (Ephemera danica) just emerged at waters surface in dun form, the first of two winged adult instars or developmental stages, Hertfordshire, England, UK, June.

Andy Sands / Mayfly (Ephemera danica) just emerged at waters surface in dun form, the first of two winged adult instars or developmental stages, Hertfordshire, England, UK, June.

Jan Hamrsky / Common burrowing mayfy nymph (Ephemera danic(b, Europe, May, controlled conditions

Nick Upton / Adult Green / Anglers drake mayfly (Ephemera danica) flies up from a stream, having just emerged from a winged 'sub-imago' stage, floating on the surface, Wiltshire, UK, May.

Konrad Wothe / Common Burrower Mayfly (Ephemera danica) on flower Germany

Piotr Naskrecki / Mayfly (Ephemera mooiana) recently emerged from subimago, Gorongosa National Park, Mozambique

Piotr Naskrecki / Mayfly (Ephemera mooiana), Gorongosa National Park, Mozambique

Mitsuhiko Imamori / Common Burrower Mayfly (Ephemera sp) on dew covered grass, Shiga, Japan