A very interesting thing about the 17-year lifespan of cicada is that it sleeps in the ground for those entire 17 years, comes out to enjoy only five weeks of life in the sun and then dies! When the young are hatched from eggs, they drop down, burrow into the ground and attach themselves to roots. And these young cicadas which are called "nymphs", remain there motionless for 17 years, sucking the sap of the roots. And then they climb the trunk of a tree, into the light, their skins split open and the mature cicada emerges.
It lives for five weeks in the sun and then dies. Though it has the longest life, it spends almost all of it in sleep!