We're in for a Cicada Double-Whammy

A swath of the country will soon be buzzing—loudly, with up to a trillion cicadas. This April will mark a first since 1803 with the dual emergence of two periodical cicada groups: Brood XIX, or the Great Southern Brood, which surfaces every 13 years, and Brood XIII, also known as the Northern Illinois Brood, which emerges every 17 years. "After this spring, it'll be another 221 years before the broods, which are geographically adjacent, appear together again," the New York Times reports, noting the dual appearance will bring the possibility of cross breeding. This could mean "the creation of a new brood set to a new cycle," which is "an extremely rare event," says Floyd Shockley, an entomologist at the Smithsonian National Museum of Natural History.

The Great Southern Brood will appear first from late April to early May in some 15 states, including Illinois, Missouri, Arkansas, Mississippi, Alabama, Georgia, and the Carolinas. The Northern Illinois Brood will surface later around mid-May to early June in Illinois, southern Wisconsin, northwestern Indiana, and southwestern Michigan. As the ground reaches 64 degrees, the cicadas emerge to molt and mate. The males emit a buzz of up to 100 decibels—"roughly equivalent to a motorcycle or jackhammer," per NBC News—to attract females who lay their eggs in slits on tree branches, some of which may break. Netting can be used to cover any plants in need of protection.

"It's a lot of singing, lots of paramours pairing up, and then lots of dying," Jonathan Larson, an entomologist at the University of Kentucky, tells NPR. The cicadas die after about four weeks, leaving behind a bit of a mess and a smell comparable to rotting nuts, says Shockley. "But rather than throwing (them) in the trash or cleaning up with street sweepers, people should consider them basically free fertilizer for the plants in their gardens and natural areas," he tells the Times. He notes pesticide should not be used on the harmless insects as these could further injure pets and other animals that feed on the bugs, in addition to bees and butterflies. "It will be intense, but short-lived," he tells the Times of the emergence. "Embrace it for the wondrous event that it is." (More cicadas stories.)