Billions and Billions of Periodical Cicadas
Image from Insects, Their Ways and Means of Living, by Robert E. Snodgrass (1930), vol. 5, Smithsonian Scientific Series, Biodiversity Heritage Library.
When soil temperatures under the ground reach a balmy 64 degrees Fahrenheit, periodical cicadas emerge in the U.S. They tend to do it in groups—whole regions containing billions of cicadas are synchronized in 17- or 13-year cycles.
In 2024, two broods of cicadas will emerge at the same time. The last time this happened was 1803 and Thomas Jefferson was President. Brood XIX are 13-year cicadas and will appear in Georgia and the Southeast. Brood XIII, 17-year cicadas, will surface in Illinois.
Find out more about cicadas from the Encyclopedia of Life and this educational resource from the Smithsonian’s National Museum of Natural History and see more images at Smithsonian Libraries and Archives. Listen to the "Ode to Cicadas" podcast episode on the emergence of Brood X and discover cicadas in the Smithsonian's collections.