Cicadas emerge after 17 years underground

Beneath your feet, for over a decade, an insect larva might be quietly growing, feeding on tree sap in the soil. Then, almost overnight, millions, sometimes billions, of these creatures emerge, transforming quiet forests into roaring soundscapes. This isn't science fiction; it's the bizarre, strategic life cycle of periodical cicadas, some species of which spend up to 17 years underground before a brief, explosive appearance above.

The mechanism behind this extended subterranean hideout is thought to be a sophisticated survival strategy against predators. By emerging in such massive numbers, and so infrequently, periodical cicadas overwhelm their enemies through sheer abundance, a phenomenon known as predator satiation. A bird or small mammal can only eat so many cicadas, and by the time they've had their fill, the vast majority of the cicada swarm has already found mates and reproduced. The long, precise intervals—13 or 17 years, which are prime numbers—also make it incredibly difficult for predator populations to synchronize their own life cycles to match the cicadas' emergence, further enhancing the insects' chances of survival.

Once above ground, the cicadas waste no time. Their primary, and often only, goal is reproduction. The males fill the air with their distinctive, often deafening, calls, which can reach over 100 decibels—louder than a lawnmower. This cacophony is a mating chorus, attracting females from all directions. After mating, the females lay their eggs in small slits they carve into tree branches. These eggs hatch into tiny nymphs that drop to the ground and burrow underground, restarting the cycle. Their adult lives are fleeting, typically lasting only a few weeks.

The ecological impact of these mass emergences is profound. They provide a sudden, massive food source for countless animals, enriching the soil with their decaying bodies, and even naturally pruning trees by laying eggs in branches, which can lead to new growth. For us, a cicada emergence is a fleeting, noisy spectacle, a powerful reminder of nature's strange rhythms and ingenious survival tactics playing out on a multi-decade scale, right under our unsuspecting noses.