The term periodical cicada is commonly used to refer to any of the seven species of the genus Magicicada of eastern North America, the 13- and 17-year cicadas. They are called periodical because nearly all individuals in a local population are developmentally synchronized and emerge in the same year. Although they are sometimes called "locusts", this is a misnomer, as cicadas belong to the taxonomic order Hemiptera (true bugs), suborder Auchenorrhyncha, while locusts are grasshoppers belonging to the order Orthoptera. Magicicada belongs to the cicada tribe Lamotialnini, a group of genera with representatives in Australia, Africa, and Asia, as well as the Americas.

Magicicada species spend around 99.5% of their lives underground in an immature state called a nymph. While underground, the nymphs feed on xylem fluids from the roots of broadleaf forest trees in the eastern United States. In the spring of their 13th or 17th year, mature cicada nymphs emerge between late April and early June (depending on latitude), synchronously and in tremendous numbers. The adults are active for only about four to six weeks after the unusually prolonged developmental phase.

The males aggregate in chorus centers and call there to attract mates. Mated females lay eggs in the stems of woody plants. Within two months of the original emergence, the life cycle is complete and the adult cicadas die. Later in that same summer, the eggs hatch and the new nymphs burrow underground to develop for the next 13 or 17 years.

Periodical emergences are also reported for the "World Cup cicada" Chremistica ribhoi (every 4 years) in northeast India and for a cicada species from Fiji, Raiateana knowlesi (every 8 years).

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