After a 17-year subterranean maturation period, billions of Brood X cicadas are emerging across the United States.

Peter Grant — Class of 1877 Professor of Zoology, Emeritus and Professor of Ecology and Evolutionary Biology, Emeritus at Princeton University — explains why they take their time underground, and how they operate once they come to the surface.

Singer Bob Dylan witnessed this arrival first-hand at Princeton, when he received an honorary degree at 1970 Commencement — which inspired the lyrics to his song "Day of the Locusts."

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