There are two groups of cicadas: dog-day cicadas and periodical cicadas. Dog-day cicadas are very dark with greenish markings and spend four to seven years underground before emerging in July and August. Periodical cicadas are dark with red eyes. They emerge in late May and early June after 14 to 17 years underground. New groups of young are born every year, so every year different generations emerge.
Female cicadas lay from 200 to 600 eggs in tiny holes made in branches and twigs in trees and shrubs. Cicada young—called nymphs—hatch from the eggs and immediately drop to burrow underground, where they attach to tree roots. The nymphs remain attached to the roots, sucking tree sap, for most of their lives. When the dormant period ends, the cicada emerges from underground at sunset, guided only by instinct, and climbs the trunk of a nearby tree. There the cicada’s skin sheds, allowing the adult cicada to emerge.
Above ground, male cicadas fill the air with shrill buzzing sounds, the result of small drum-like plates on the abdomen that the cicada vibrates rapidly. While many people find the sound annoying, the male cicada uses it to attract female cicadas for mating. Both male and female cicadas die after about five weeks above ground.