The Cicadas are coming!

This spring and summer, people in parts of the American Midwest and South will get to experience a numerically magnificent wildlife event: a rare double emergence of periodical cicadas. With the arrival of Brood XIX and Brood XIII, trillions of harmless, baby-carrot-size insects will be singing their hearts out from Wisconsin to Louisiana, Maryland to Georgia, and many places in between.

The last time these broods co-emerged, the year was 1803, Thomas Jefferson was president, and the Louisiana Purchase had just been completed — which means many of the states where cicada love songs will soon fill the air were not even officially part of the nation yet.

As impressive as that is, this year’s entomological phenomenon will be extra-special for researchers hoping to unravel the evolutionary mysteries of bugs that only crawl out of the ground in roughly 13-year and 17-year intervals.