An adult Brood X Magicicada septendecim in Princeton, New Jersey. Image from 2004. Image credits: P. M. Jacoby.
Periodical cicadas spend 99.5% of their life underground.
Most of them live in large broods that go underground for cycles of 17 or 13 years — though some have different timings.
During these periods, they live as nymphs that feed on fluids from the roots of trees.
When the time is right, the individuals in a brood emerge, all at once, and live overground for only a few weeks.
Cicadas likely developed this evolutionary strategy to avoid predators. Using prime numbers for their emergence makes it difficult for predators to adapt.
