Foto: Piotr Kusy

Mayfly (Ephemeroptera)

Mayflies are unique insects with a delicate and slender physique. They reach a body length from 2 to 40 mm. As adults they survive only for a few days. Most of their lives, even a few years, they spend in the water in the larval stage. During this time they moult and grow, feeding on plant food. The best development conditions for them are in cool, clean flowing water with good oxygenation. At the beginning of the summer, mature larvae emerge to the surface of the water. Here they shed their old skin and after drying the wings they soar into the air. After a short time they moult for the last time, reaching full maturity. The presence of two winged forms of mayflies makes them distinct from other flying insects. Adults do not eat and their digestive tract serves as the aerostatic organ. The mating rituals of mayflies are very spectacular. The females fly into a swirling and loud cloud of males performing the mating dance. Most insects die shortly after placing eggs in the water. Mayflies are eaten by fish, amphibians and birds. For people they are perfect fish bait. Mayflies are very sensitive to any changes in the aquatic environment. Their presence indicates that the water is very clean. Once mayflies were common in the rivers of Europe. Today they are on the Red List of Threatened Species.