Get ready to plug your ears, because the cicadas are coming! This year marks the emergence of Brood X, a generation of 17-year periodical cicadas that have been feeding and growing underground since 2004. If Brood X’s circadian rhythms are correct, then billions of cicadas will wake up and emerge from the ground this spring. And with 17-years’ worth of pent-up energy, these cicadas are sure to be busy.
Brood X comprises three species of cicada that are characterized by their large black bodies, dark red eyes, and signature, ear-splitting rattling noises. The sound—or “song” if you’re an entomologist—is a mating call from the males. Females respond by snapping with their wings, which attracts a swarm of males toward them. So when you encounter low-flying cicadas this spring—and you probably will—it’s just because they’re seeking a mate.
“Cicadas are not out to get people,” says Sarah Kent, a community outreach manager at Great Parks of Hamilton County. “There’s just going to be hundreds and hundreds of them in everyone’s presence.” While you may not be ecstatic to be surrounded by these loud, invasive bugs, cicadas are at an advantage: Due to their large numbers, predators simply can’t eat them all. Evidently, cicada years are bountiful for a lot of animals, from turkeys and chickens to songbirds, opossums, and raccoons. “Scientists will note a population boom in other animals because they’re so well fed,” Kent says, adding that after the last 17-year cycle, “Cincinnati had a really booming rat population.”
The periodical cicadas spend most of their lives buried roughly a foot underground, where they feed on the roots of trees and plants until they’re ready for the mating season. When the cicadas finally do emerge, their only goal is to mate and lay their eggs. After the cicadas lay their eggs, which the females plant into the twigs of trees, their lifecycle is complete. The adults die within a few weeks, and the sticks that carry their young will fall to the ground so they can burrow down and begin their own 17-year recess. “That’s essentially their lifecycle above ground,” Kent says, “the majority of it is underground.”
The cicadas are expected to appear in late April to mid-May, and they know it’s time to emerge when the ground temperature reaches 64 degrees Fahrenheit. Once the cicadas break ground, they’ll be widespread for about six weeks all across the eastern U.S., ranging from Michigan to Georgia. In a podcast from NPR, an entomologist estimates that in densely populated areas, there could be as many as 1.5 million cicadas per acre.
“The amount of them everywhere is definitely going to be a little intimidating,” Kent says, “but I always encourage people to just get close and observe them so that they’re not as intimidated.” One way to get closer with cicadas is with the Cicada Safari app, which was created by Gene Kritsky, Ph.D., of Mount St. Joseph University. The app turns users into citizen scientists—take photos of the cicadas you encounter with your phone, and they’re logged in a database that scientists can study. Brood X will be widespread, and Kent says that “the more data we have, the more we can actually track where the populations are and where they are going, because they seem to be spreading.”
Scientists still have much to learn about these intriguing bugs, and there is still no definitive answer on how the cicadas know when 17 years have passed and that it’s the correct year to emerge. “While that’s not a completely known fact,” Kent says, “it has been recorded for almost 200 years.” So when they finally start burrowing up later this spring, be ready for a rare event that only comes around once in a generation.