Whose studies first revealed that cicadas emerge on 13-year and 17-year cycles?

Periodical cicadas fascinated early American naturalists because they appeared in vast numbers only at long intervals. Historical observations documented 13-year and 17-year brood cycles in different populations. These synchronized emergences puzzled scientists for generations and became a classic topic in entomology. The long life cycle likely helps cicadas avoid predators and the pressures of annual timing. Their study remains important for understanding insect evolution, life history, and population dynamics.