Trillions' of cicada set to swarm northeastern US after 17 years underground

Cicadas in the northeastern US emerge after 17 years underground, where they feed on tree root sap. Upon surfacing, they live for about four weeks, primarily to mate. Males attract females with acoustic sounds, and females respond by snapping their wings. After mating, females lay hundreds of eggs on tree limbs. Once hatched, nymphs fall to the ground, burrow, and feed on tree roots for up to 17 years before emerging again.

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