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A cicada sheds its nymph shell in Chevy Chase, Maryland during a Brood X emergence in May 2021.
Carolyn Kaster/AP file photo
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Carolyn Kaster/AP file photo
A cicada sheds its nymph shell in Chevy Chase, Maryland during a Brood X emergence in May 2021.
Carolyn Kaster/AP file photo
Much of the eastern United States can prepare for what one entomologist describes as a “wonderful, spooky Mardi Gras” this spring.
The event that Jonathan Larson, an entomologist at the University of Kentucky, refers to is when two broods of cicadas appear simultaneously in states from Virginia to Illinois from late April to June.
With the longest known insect life cycle, cicadas spend most of their lives underground in immature larval form, then emerge above ground every 13 to 17 years for a brief adult life. A swarm consists of several species of cicadas that come together in the same cycle.
Although cicadas are valuable food for birds and small mammals, their deafening calls can be irritating when they are in large numbers, and their corpses lying on the ground can be a nuisance. When the northern Illinois swarm last appeared 17 years ago, “they were so numerous that Chicagoans had to shovel them out to clear their sidewalks and streets,” said Floyd Shockley, an entomologist and the department's collection manager. said. PhD in Entomology from the National Museum of Natural History.
![Brood](https://media.npr.org/assets/img/2021/05/25/collect_sq-79c92f7277e5ec614495c3f363675c0d382a82b0-s100-c15.jpg)
Mount St. Professor Emeritus of Biology at St. Joseph University A Tale of Two Broods: Emergence of Periodic Cicada Swarms XIII and XIX in 2024.
The last time the two bands, Brood XIX and Brood XIII, appeared simultaneously was in 1803. Shockley says their appearance makes it “a very rare, once-in-a-lifetime event.”
Brood XIX, known as the Northern Illinois Brood, includes three different species of cicadas and appears every 17 years. The Great Southern Brood, or Brood XIII, consists of a 13-year cycle and includes four different species of cicadas.
Shockley said Great Southern Brood will begin appearing from Virginia to Alabama and Mississippi across 15 states, mostly in the South, from late April through the first or second week of May.
![No, you don't have to worry about your dog (or cat) eating cicadas.](https://media.npr.org/assets/img/2021/06/03/gettyimages-1233132195_sq-a50b8c729bc3c145568223c0adb4aa0a24cad168-s100-c15.jpg)
For Northern Illinois Brood, Shockley said people will start seeing these cicadas from mid-May through the first week of June. This swarm will be highly concentrated in four states, including Illinois, parts of Wisconsin, Indiana and parts of Michigan.
Kritsky said that due to the double emergence of the two swarms, “we're probably going to see billions of cicadas” across the east. You can hear or see cicadas in the area until September, but perennial cicadas disappear by June and their songs are replaced by annual cicadas for the rest of the summer.
Once the ground reaches its optimal temperature of 64 degrees Fahrenheit, the insects move to nearby trees and shed their bark, Kritsky said. It takes about four to five days for adult males to start singing, but once they do, their songs can be louder than a jet engine.
Male cicadas “produce a chorus that attracts females to the trees,” Larson says. “Then they will pair up and sing a courtship song.” They sing to female cicadas individually to persuade them to mate. After mating, the female cicadas lay eggs in the tree and then die, covering the tree's stump and leaving a smell that Kritsky described as “delicate, rotten Limburger cheese.”
This cycle begins when cicada eggs fall from a tree and return to the ground for 13 to 17 years. Cicadas spend several years underground in an immature state, but the adult lifespan is only 4 to 6 weeks.
![The cicadas have come](https://media.npr.org/assets/img/2021/04/27/cicada1_sq-60fe7096cdb96142b8544021140e6a58a306e6ce-s100-c15.jpg)
“This is a really big, scary Mardi Gras,” Larson says. “There’s a lot of singing, a lot of lovers pairing up, and a lot of death.”
This spring, the two flocks will mostly be separated by time and location, but in Illinois, “they'll overlap for a few weeks,” Shockley says. This overlap, he says, results in some Illinoisans hearing all seven species in both groups singing their cacophonous mating calls together. Additionally, Shockley said, this duplication could result in “an extremely rare opportunity where genetic crosses between 13-year cicadas and 17-year cicadas could lead to the emergence of new offspring.”
All experts interviewed by NPR emphasized that the temporary appearance of bugs is not harmful to humans or pets. The amount may be shocking if you're in certain high-density areas, but it's unlikely to bite or sting, Larson says. “Your pet will probably try to eat it,” he adds. “And they’ll be okay.”
Shockley added that you shouldn't spray insecticides on bugs. The chemicals may affect birds and small mammals that eat the cicadas. “Or they may attack non-target things like butterflies or bees that you actually want to have around your home,” he says.
Larson said people “may be disgusted by this situation,” but emphasized that it was a unique and beautiful natural spectacle that could not be found anywhere else in the world.
Kritsky, referring to the British naturalist and broadcaster, described the short-lived appearance of cicadas as “like having a David Attenborough special in your backyard.” “If you're lucky enough to live in an area where this is happening, take your kids there. Watch this.”