periodical cicada, (genus Magicicada), genus of seven species of cicadas known for their unusual highly synchronized life cycles and raucous choruses. Periodical cicadas are native to the eastern and midwestern United States but are not present aboveground every year. In what are among the longest life cycles of any insects, periodical cicada broods emerge in spring only every 13 or 17 years, with millions of insects materializing from the soil in a matter of weeks and dying shortly thereafter. Three species of periodical cicadas (Magicicada septendecim, M. cassini, and M. septendecula) emerge every 17 years, while the other four species ...(100 of 1093 words) Access the full article Help support true facts by becoming a member. Subscribe today!