Last month, more than a trillion creatures started crawling out of the ground. Don’t worry—they’re not zombies! They’re insects called cicadas (sih-KAY-duhz).
Most species of cicadas come out once a year. But this spring, two huge broods, or groups, have arrived in the Midwest and Southeast. Brood XIX emerges once every 13 years. Brood XIII comes out every 17 years. This is the first time in 221 years that the two broods have arrived at the same time.