Get your white noise machines ready: The eastern half of the country is about to be abuzz with a phenomenon that hasn’t happened since 1803. A dual cicada emergence—in which the seventeen-year Brood XIII (or the Northern Illinois Brood) bursts forth from the earth in tandem with the thirteen-year Brood XIX (aka the Great Southern Brood)—is revving up now and running through the end of May.
Illinois and the Midwest will see the heat of the double action, but the arrival of Brood XIX, which constitutes the majority of bugs, will touch most Southern states, including Georgia, North Carolina, South Carolina, Alabama, Mississippi, Tennessee, Arkansas, and Kentucky. “When cicadas come up by the hundreds of billions, they satiate every predator,” says Matt Kasson, who teaches forest pathology at West Virginia University in Morgantown and is often in the field gathering cicadas during such events. That is the bug’s evolutionary strategy, and it works: They are eaten by the million, sure, but the numbers are so overwhelming that plenty are left to reproduce. Brood XIX, which boasts the largest geographical distribution of any of the fifteen broods in existence, includes four different species of thirteen-year cicadas, all of which will start their crawl upward through the soil once its temperature hits 64 degrees.
What does that mean for your yard?
Annoyance aside—each insect can emit a hundred-decibel buzz, as loud as a jackhammer or motorcycle—it’s not as devastating as it sounds to have millions of screaming insects careening around. After all, they are not here to eat. “When they emerge, their sole purpose in life is to reproduce,” Kasson explains. A male cicada uses tymbals on its abdomen, which serves as a resonating chamber, to call and impress the females. If he attracts a mate, she’ll lay eggs in twigs and branches in trees.
“The only thing people should worry about is if they have a prized tree or shrub that’s small and could be damaged from their egg-laying in the twigs and stems,” says Matt Bertone, an entomologist at North Carolina State University. Using a mouthpiece called an ovipositor that works like a tiny knife, female cicadas cut small slits in tree branches for the eggs. That branch might wilt from the egg-laying point outward, but generally only young or unhealthy trees are at any risk of death. If you do have such a tree, wrap a net around the plant and tie it off around the stem to deter the cicadas, Bertone advises. “Otherwise, despite the nuisance and noise, there’s nothing to worry about.”
Of course, there is a striking—if temporary—mark on the landscape: After achieving their singular goal of reproduction, the adult insects will die, resulting in crunchy exoskeletons lying around by the millions. But they serve a purpose. “That’s a lot of debris, and it’s important for nutrient cycling,” Kasson says. “There’s a huge influx of nitrogen into the soil when they die.” After all, cicadas have spent decades feeding off sap underground, waiting to emerge once all the predators’ generational knowledge of them has been lost. (If hungry animals like birds and mammals don’t know they’re coming, the insects have the best chance of overwhelming them.) Their deaths provide a huge boost for vegetation, so don’t be too quick to sweep them from your yard. “You can actually see the benefit in tree rings,” Kasson says. “After an emergence year, there’s a larger tree ring associated with that huge influx of nutrients.”
Meanwhile, the eggs will hatch in about six weeks, and tiny cicada nymphs the size of rice grains will plummet to the ground and start to dig. Once they’re deep enough, they’ll attach to a tree root and spend thirteen or seventeen years drinking sap and growing—until it’s time to surge upward again. “This is a phenomenon that only happens in North America,” Kasson says. “It’s amazing to stand in a field covered in thousands of cicadas, hearing that cacophony.”
Read more about cicadas’ life cycle here, and find a list of counties where Brood XIX will emerge here.
