Mayflies (Ephemeroptera) cause lots of problems for the trout fisherman as they all look pretty much the same! There are 46 species of mayflies in the Uk and 2,500 world-wide. The trout fisherman needs simply to know it is a large yellow mayfly or brown mayfly unlike true flies (Ditera) where flies differ enormously between families.
Their hatch is an exciting time for a trout fisherman. When hatching trout feed voraciously on the larvae, winged and spent mayflies and flies are designed specifically to match the different stages of this fly.