Image from Insects, Their Ways and Means of Living, by Robert E. Snodgrass (1930), vol. 5, Smithsonian Scientific Series, Biodiversity Heritage Library.
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 X is emerging after 17 years underground. Find out more about cicadas from the Encyclopedia of Life and see more images at Smithsonian Libraries.
