only insects to have two distinct adult stages: a subimago, which moults into the imago. Rhithrogena germanica has the longest–lasting subimago stage of any mayfly, allowing up to four days before moulting into the imago, during which time the subimago rests in a tree near the river it emerged from. Mayfly adults have no functioning mouthparts and, after reproducing, they die. Fly fishing The March brown is "probably the most famous of all British mayflies", having been copied by anglers to catch fish for over 500 years. It is taken by trout. References Mayflies Insects of Europe Insects described in 1885