Periodical cicadas

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.