The Insects That Wait 17 Years
For 17 years they wait underground. Then, in a few nights, billions climb out of the soil at once, and the woods roar with their song.
What was reported
Periodical cicadas live in the eastern United States. Their young spend 13 or 17 years underground, feeding on tree roots. Then, in a single spring, a whole brood emerges within days, crawling up tree trunks in the dark, shedding their skins and flying off with red eyes and orange wings.
For a few weeks, the males sing in huge choruses, a pulsing, whining roar that can be as loud as a lawnmower. When English settlers first saw them in the 1600s, they thought they were a biblical plague of locusts. In 2021, the huge 'Brood X' emerged across a dozen states.
Explanations offered
By emerging all at once in such enormous numbers, the cicadas overwhelm predators: birds and animals can eat only a fraction of them. Their prime-numbered life cycles of 13 and 17 years may help them avoid predators with shorter cycles. They're harmless to people.
- When
- Every 13 or 17 years; Brood X in 2021
- Where
- Cincinnati, Ohio, USA
- Witnesses
- Millions of people in the eastern United States
- Status
- Explained
Famous cases are real, widely reported events. Each file sets out what witnesses said and the explanations that have been offered, without taking a side.
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