Periodical cicadas

Definition

Members of the genus Magicicada, a group of seven cicada species in eastern North America characterized by extraordinarily long, synchronized life cycles of 13 or 17 years. All individuals in a local population emerge as adults in the same year after developing underground as nymphs feeding on xylem fluids from tree roots. This developmental synchrony—unique among cicadas and rare among insects—creates mass emergences that saturate predator populations, a strategy known as predator satiation. The 13-year forms are generally associated with more southern ranges, while 17-year forms occur farther north, though both types include multiple species with distinct songs and morphological differences.

Etymology

From Latin periodicus 'recurring at intervals' + cicada, referring to the fixed, multi-year emergence cycle

Example

Brood X of the 17-year periodical cicada (Magicicada septendecim) emerged across fifteen U.S. states in 2021, with densities reaching over one million individuals per acre in deciduous forest habitats.

Synonyms

• Magicicada
• 13-year cicadas
• 17-year cicadas

Related Terms

• cicada
• predator satiation
• Brood
• xylem feeding
• nymph
• Emergence
• Magicicada septendecim
• Magicicada cassini

Usage Notes

The common name 'locust' is a persistent misnomer from early colonial accounts and should be avoided; locusts are grasshoppers (Orthoptera) with fundamentally different biology. 'Periodical' specifically denotes the fixed-interval, synchronized emergence—do not confuse with 'periodic' in the general sense of recurring. The seven species are partitioned into three species groups (decim, cassini, decula) with different male calling songs and slight morphological distinctions. Brood designations (e.g., Brood X, Brood XIX) track geographically distinct populations that emerge in the same year, not taxonomic species; a single brood may contain multiple species, and the same species appears in multiple broods.