Alien for one day since ages

Mayflies, also known as fishflies in Canada, are aquatic insects like dragonflies and damselflies. Their immature stages are aquatic fresh water forms called "naiads" or "nymphs" as shown in this picture.

They are part of an ancient group of insects living during the Carboniferous (more than 300 Million years ago) and exhibit a number of ancestral traits that were probably present in the first flying insects, such as long tails and wings that do not fold flat over the abdomen.

Their presence indicates a clean, unpolluted environment. They are unique among insect orders in having a fully winged terrestrial adult stage, the subimago, which moults into a sexually mature adult, the imago.

Mayflies "hatch", they emerge as adults, from spring to autumn, not necessarily in May. Fly fishermen make use of mayfly hatches by choosing artificial fishing flies that resemble the species in question.

The brief lives of mayfly adults have been noted by naturalists and encyclopaedists since Aristotle and Pliny the Elder. The German engraver Albrecht Dürer included a mayfly in his 1495 engraving The Holy Family with the Mayfly.