In contrast to that of the nymph, the life of adult cicadas is very short, lasting only a few weeks. After mating, the adult female cicada lays its eggs. It does this by piercing plant stems with its ovipositor (egg-laying spike at the tip of the abdomen) and inserting the eggs into the slits it has made. The eggs hatch into small wingless cicadas which are known as nymphs. They fall to the ground and burrow below the surface. Here they live on the sap from plant roots for a period which may last several years. They shed their skin at intervals as they grow.
When the nymph reaches full size it digs its way to the surface with its front legs, which are specially adapted for digging. It generally surfaces about nightfall in late spring or early summer. The nymph then climbs on to a tree trunk or other object and sheds its skin for the last time. The fully-winged adult cicada which emerges leaves its old empty nymphal skin behind.
Here's a collection of nymphal skins: