Mayfly

I coincidentally spotted a large fly in the tree.
I learned, that it is a mayfly. In German it is called "Eintagsfliege" = "one Day Fly" and that what it is. After about two years in the water as nymph, it emerges and lives only one day as a fly to mate and breed. They do not even have a mouth to eat. Fascinating! Have a look here for more information :-D