Periodical Cicada (17-Year)

Magicicada is a genus of seven species of cicada native to eastern North America that share an extraordinary life history: each species spends either 13 or 17 years underground as a nymph, feeding on tree-root sap, before emerging to molt, mate, and die — all within a few weeks above ground. Emergences are synchronized across vast geographic broods so that an entire region experiences a cicada outbreak in the same summer. Brood XIII (the 'Northern Illinois Brood') and Brood XIX (the '13-year Great Southern Brood') famously co-emerged in 2024, an event that had not occurred since 1803. The choice of 13 and 17 is mathematically deliberate: both are prime numbers. A predator with a 2-, 3-, 4-, or 5-year cycle cannot synchronize its peak with the cicada's emergence. The strategy is called predator satiation by prime cycle. During emergence, populations can exceed 1.5 million cicadas per acre, and the collective sound from singing males can reach 100 dB. Despite the spectacle, the cicadas are entirely harmless — they don't bite, sting, or transmit disease. They are also a major nutrient pulse for forest food webs.