Naturalists have already spotted the first arrivals in a rare phenomenon during which cicadas will emerge across more than a dozen US states, including populous areas.
Parts of the United States are about to experience a rare natural phenomenon with the simultaneous emergence of two enormous adjacent broods of periodical cicadas. The two broods - one concentrated in U.S. Midwestern states and the other in the South and Midwest, with a small area of overlap in Illinois - emerge together only once every 221 years.