Periodical cicadas
Synchronized emergences every 13 or 17 years.
Periodical cicadas are seven species belonging to the genus *Magicicada*, found exclusively in eastern North America. They are called "periodical" because nearly all individuals within a local population develop in lockstep, emerging as adults in the same year after either 13 or 17 years underground. Despite being commonly misnamed "locusts," they are true bugs (order Hemiptera), not grasshoppers. The genus is part of the cicada tribe Lamotialnini, which also includes species in Australia, Africa, and Asia. These insects spend roughly 99.5% of their lives as nymphs beneath the soil, feeding on xylem fluids from the roots of broadleaf forest trees. In the spring of their 13th or 17th year, mature nymphs emerge synchronously and in vast numbers between late April and early June, depending on latitude. The adult stage lasts only four to six weeks. Males gather in chorus centers to call for mates; females lay eggs in the stems of woody plants. Within two months of emergence, the adults die, and the eggs hatch later that summer, with new nymphs burrowing underground to begin the next cycle. Periodical emergences also occur in other cicada species elsewhere: *Chremistica ribhoi* (the "World Cup cicada") emerges every four years in northeast India, and *Raiateana knowlesi* emerges every eight years in Fiji. Adult *Magicicada* have red compound eyes, a black thorax, translucent wings with orange veins, and abdomens that may be black, orange, or striped. They are about 75% the size of annual cicadas in the same region. They cannot sting and rarely bite; their mouthparts are adapted for piercing plants, not animals. Oviposition by females damages small twigs, but mature trees usually survive, though young trees may need protection with fine mesh netting.
- field
- Entomology
- known_for
- Synchronized 13- and 17-year life cycles
- species_count
- 7
- genus
- Magicicada
- region
- Eastern North America
Lore & Background
Periodical cicadas spend about 99.5% of their lives underground as nymphs, feeding on xylem fluids from tree roots. In the spring of their 13th or 17th year, mature nymphs emerge synchronously between late April and early June, depending on latitude. The adults live only four to six weeks, during which males form chorus centers to attract mates, and females lay eggs in woody plant stems. After two months, the adults die, and the eggs hatch, with new nymphs burrowing underground to begin the cycle again. The winged adult has two red compound eyes, a black dorsal thorax, and translucent wings with orange veins. Adults are 2.4 to 3.3 cm long, with females slightly larger than males. Males produce species-specific calling songs; the decim species' call resembles 'weeeee-whoa' or 'Pharaoh,' while cassini and decula species intersperse buzzing and ticking sounds. Cicadas cannot sting and do not normally bite, though their proboscis can pierce human skin if handled, causing pain but no harm. Oviposition by females damages pencil-sized twigs, but mature trees rarely suffer lasting harm. Young trees can be protected with mesh netting. The nymphs track years by detecting changes in tree xylem caused by leaf abscission; experimentally inducing two leaf cycles in one year caused emergence after 16 years instead of 17.
Reader's Guide
Periodical cicadas are significant for their extreme life-cycle synchronization and long developmental periods, which serve as a survival strategy called predator satiation. By emerging in massive numbers—sometimes over 1.5 million per acre—they overwhelm predators, ensuring enough individuals survive to reproduce. This phenomenon has fascinated biologists and the public alike, as emergences are predictable and dramatic events. The 13- and 17-year cycles are among the longest known for insects, and the timing is linked to environmental cues like soil temperature and tree physiology. Their presence influences forest ecology through nutrient cycling and twig damage, and they are a cultural touchstone in regions where emergences occur. The term 'periodical cicada' distinguishes them from annual cicadas, which have shorter, overlapping life cycles. Despite being called 'locusts,' they are true bugs (Hemiptera), not grasshoppers. Their study has contributed to understanding of life-history evolution, predator-prey dynamics, and phenology.
Did You Know?
- Periodical cicadas spend about 99.5% of their lives underground as nymphs.
- The call of decim periodical cicadas is said to resemble 'weeeee-whoa' or 'Pharaoh'.
- Cicadas cannot sting and do not normally bite; their proboscis can pierce human skin but is not harmful.
- Periodical emergences also occur for a cicada species in Fiji every 8 years and for the 'World Cup cicada' in northeast India every 4 years.
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