Cicadas 2024 How Long Do They Last. Six to eight weeks after the eggs are laid, the nymphs hatch and fall to the earth. Periodical cicadas, which only live in midwestern and eastern states, spend either 13 or 17 years underground before coming out as adults in mass, synchronized emergences, while annual cicadas, which live all over north america and other parts of the world only spend a few years underground before appearing above ground in smaller,.
Once the soil in those. Generally, cicadas are harmless, adams said.