Dobsonfly

http://en.wikipedia.org/wiki/Dobsonfly

English Name: Dobsonfly
Family: Corydalidae (Dobsonflies)
Genus: Corydalus
Species: cf. leteus

The dobsonfly's immature larval stage is aquatic, living 3-5 years in non-polluted, fast-running, well oxygenated rivers before metamorphosing. It's thought that the adults don't even eat, though they make drink a bit.