Get ready. Trillions of chirpy, red-eyed periodical cicadas are getting ready to emerge from underground in a rare double emergence event. These specific types of cicadas crawl out from below the ground every 13 or 17 years and can make as much noise as a jet engine.
While there are 3,400 known species of cicadas, only nine of them have the tendency to disappear underground then reemerge all at the same time. Seven of these nine periodical cicada spears are found in the United States. Even though it is not happening all across North America, it is still a huge natural event that’s worth keeping an eye on.
[Related: This gnarly fungus makes cicadas hypersexual.]
“I would put the periodical cicadas as a natural phenomenon in the same category as April’s total solar eclipse,” Penn State University entomologist Michael Skvarla tells PopSci.
What is a brood of cicadas?
A brood is another term for a group of periodical cicadas that emerge every 13 or 17 years. Scientists use roman numerals to differentiate between various broods in North America. This year, Brood XIII (aka the Northern Illinois Brood) and Brood XIX (the Great Southern Brood) will emerge at the same time.
The Northern Illinois Brood is a 17 year group and stretches across parts of Indiana, Wisconsin, Iowa, and northern Illinois. The Great Southern Brood emerges every 13 years and is primarily located in Arkansas, Missouri, Tennessee, Alabama, George, North Carolina, South Carolina, and importantly, southern Illinois.
[Related: Cicadas pee in jet streams like bigger animals.]
“This year is kind of special because we have the emergence of two broods,” says Skvarla. “ We have one 13 year brood and one 17 year brood emerging. Because they’re coming out every 13 or 17 years, they don’t sync up very frequently.”
When will they emerge?
They will start to emerge as soon as the surrounding soil has reached 64 degrees Fahrenheit. That usually occurs anytime between late April and June and the cicadas will stay around through July.
These cicadas hatched from eggs that were laid in 2011 and 2007. They fell from the trees as newborns and burrowed into the ground where they hunkered down and fed on xylem sap and tree roots as they grew.
Where will the broods overlap?
The real “cicadapocalypse” will primarily affect the unlucky few in parts of Illinois where both broods will emerge simultaneously.
Even though it is not happening all across North America, it is still a huge natural event. “I would put the periodical cicadas as a natural phenomenon in the same category as April’s total solar eclipse,” says Skvarla.
This type of overlap is also incredibly rare and has not occurred since 1803, when Thomas Jefferson was president and had just purchased the Louisiana Territory from France.
[Related: Fiber optic cables can pick up cicadas’ droning din.]
What do they do when they emerge?
Cicadas come up to mate for several weeks and then die. The males send out their mating song by vibrating the small flaps on their abdomen called tymbals. Females will respond by flicking their wings. Eggs will be laid in trees and the hatchlings will burrow under the ground, beginning the whole process over again.
Why do cicadas emerge on these strict schedules?
“The 13 and 17 year lifecycle is interesting, because both are prime numbers. We aren’t really sure why they’ve hit upon these prime number years,” says Skvarla. “There’s speculation that it might be because it’s harder for the broods to sync up the way that they’re doing this year.”
More synching up between broods could lead to less genetic diversity if interrelated bugs are mating with one another. Since they don’t emerge very often, it is difficult for scientists to study their peculiar calendars.
“You can spend your entire career and only see the same brood emerge two or three times,” said Sklarva.
[Related: Baby Brood X cicadas are headed underground. What lies ahead is still a mystery.]
What do cicadas eat?
They spend their time underground munching on tree roots. They will not be destroying plants or crops when they emerge.
Can you eat cicadas?
Yes, and there are several recipes that you can try.
“Cicadas kind of taste like shellfish like shrimp or lobster. It’s got kind of a crunchy, shrimpy flavor,” says Skvarla. “It doesn’t have the same consistency because cicadas have more shell and most recipes typically fry up the shell. With lobster or shrimp, you typically take the shell off.”
It is also not dangerous if your dog eats a few of them while out on a walk.
