Cicada molting

In the final nymphal instar, they construct an exit tunnel to the surface and emerge. They then molt (shed their skins) on a nearby plant for the last time and emerge as adults. The abandoned skins remain, still clinging to the bark of trees.

When I saw this I wondered and asked a friend. Thats when I got to know this interesting fact. There could be many more such life cycle stages in many other species as well. 

Here is an animated picture of how the molting happens:
 http://en.wikipedia.org/wiki/File:Cicada_molting_animated-2.gif

more to wonder