![{{{caption}}}](http://upload.wikimedia.org/wikipedia/commons/thumb/4/49/Rhithrogena_germanica_subimago_on_Equisetum_hyemale.jpg/244px-Rhithrogena_germanica_subimago_on_Equisetum_hyemale.jpg)
Mayflies (subimago of Rhithrogena germanica pictured) comprise around 2,500 species of insects which belong to the Order Ephemeroptera. They are aquatic insects whose immature stage usually lasts one year in fresh water, while the adults are short-lived, surviving from a few minutes to a few days.