Billions and Billions of Periodical Cicadas
When soil temperatures 8 inches under the ground reach a balmy 64 degrees Fahrenheit, periodical cicadas emerge on the U.S. East Coast. They tend to do it in groups—whole regions containing billions of cicadas are synchronized in 17- or 13-year cycles. This year, Brood V will emerge west of Washington, D.C., in Ohio, Pennsylvania, West Virginia, Virginia and Maryland. Find out more about cicadas from the Encyclopedia of Life and see more images at Smithsonian Libraries.