This spring, billions of cicadas will dig their way out of the soil across most of the Midwest and Southeast, filling the air with their cacophonous soundtrack.
Starting in late April, two major broods of cicadas that show up on 13- and 17-year cycles will crawl out of the soil and head to treetops to sing and mate. It’s the first time these two broods have emerged at the same time in 221 years.
The males will die almost immediately after mating. The females will live just long enough to build nests in the trees and lay eggs. By the time those eggs hatch, the adults will have died, and the young “nymphs” will burrow back underground, starting the cycle again.
This many cicadas emerging at once is like spotting a rare comet, said Zach Schumm, an insect diagnostician at Iowa State University.
“This is a really weird phenomenon that we only get to see a few times in our lives,” Schumm said.
An unusual life cycle
There are many species of annual cicadas that are spotted every summer across much of the country.
Then, there are periodical cicadas that come in waves. The seven species of periodical cicadas show up on 13- or 17-year cycles, spending most of their lives underground, but their chorus could be louder this year when their life cycles sync up for the first time in centuries.
There are two broods emerging this spring, making it a rare event. Brood XIII emerges from the ground every 17 years, while Brood XIX makes an appearance every 13 years.
The last time these broods appeared at the same time, Thomas Jefferson was president, the Louisiana Purchase was completed and Ohio had just become the 17th state.
These two cicada broods won’t be seen at the same time for another eight generations.
In these particular broods, young cicadas, called nymphs, feed on sap from tree roots underground for 13 or 17 years, depending on the species’ life cycle. They spend their final weeks underground digging their way out.
Environmental cues such as soil temperatures alert them when it’s time to emerge, so they tend to appear sooner in places that warm up earlier.
Once they surface, they only live between four and six weeks — a race against time to ensure another generation of offspring.
They look for mates with their five eyes and rely on the synchronized mating calls of male cicadas, said Tamra Reall, a horticulturist at the University of Missouri Extension. It can be louder than a jet engine, helping explain why cicadas are drawn to the drone and vibrations of power tools and lawn mowers.
Safety in numbers
The 13-year brood, XIX, also known as the Great Southern Brood, includes four species that will be spotted from southeastern Iowa down into Louisiana and across the southeastern U.S.
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