Larvae feed on the sap from tree roots. They emerge from the ground and molt into adult form. Their brown, hollow, crunchy, molted exoskeletons are often left clinging to tree trunks, window screens, wooden fences, plant stems and even blades of grass.
Adults do not feed at all; instead they devote their time and energy to reproductive efforts. Cicadas can be annual, coming back every year, or periodical (coming every 5, 10, 13, or 17 years) depending on the species and the climate.