Illinois is hit with cicada chaos. This is what it's like to see, hear and feel billions of bugs

"What you saw was biblical," said biologist Gene Kritsky, who has been chasing periodical cicadas for 50 years, yet was still amazed by the 3 to 5 million cicadas crowding a small patch of Ryerson Conservation Area north of Chicago. "There are things I've seen this time that I've never seen before."

It's an only in the United States spectacle, the last of the triple crown of rare forecasted natural wonders.

First, there was April's solar eclipse, followed by May's Northern Lights unusually far south. Now the great dual periodical cicada emergence of 2024 — an event of a magnitude not seen since 1803 — has burst from below to join the earlier shows in the sky. It's lasting weeks longer than the other two fleeting natural rarities, but in many places the cicada invasion is starting to wind down.

The males are singing for sex and won't stop until they get a female cicada's flapping wing consent. There were places in Illinois the decibel level hit 101, louder than a lawnmower, flowing in waves as an ever-present buzzing drone that seems like aliens descending in a science fiction movie. It is punctuated by bursts of the deeper-toned call "fffaaaro, fffaaaro."

The sound abounds in the suburbs of Chicago, such as Oak Brook, but has already faded farther south in the state, including where two broods overlap. In an asphalt-laden DuPage County shopping plaza, cicadas mobbing the branches of the only tree drowned out the next door automated car wash's whirring hoses and spinning brushes.

David Quinn, visiting the Chicago area from Northern Ireland, said, "whenever we were driving, we were thinking there was something wrong with the car. All that noise. It's the bugs."

Buggy tourismCicada chasers in 18 Midwestern and Southern states have submitted photos of the bugs to the Cicada Safari app, mostly concentrated in two areas, each an emergence of different broods. The Northern Illinois brood, called XIII and coming out every 17 years, is extra dense, with as much as 1.5 million bugs per tree-covered acre — which is nearly a billion per square mile — in some places like Ryerson, Kritsky said. The Great Southern Brood, which arrives every 13 years, stretches from Virginia to Missouri and southern Illinois to Georgia.

In Central Illinois, especially around Springfield, the two broods just about overlap. But it's hard to tell which brood a cicada belongs to.

At the Lincoln Memorial Garden in Springfield, Executive Director Joel Horwedel figured he'd put up a pushpin map of the United States to track where visitors came from. He wasn't thinking big enough. At the bottom of the map under a scrawl of "Out of USA" are "Japan Belgium Lithuania Germany England Japan (Kyoto)."

"It has been truly incredible how many people we're getting," Horwedel said.

U.S. Department of Agriculture research entomologist Rebecca Schmidt said usually when she gets calls about bugs, it's something bad and scary, like murder hornets. Periodical cicadas are different and "people are coming to us for good reasons, like 'tell us more, we're very excited, enthusiastic about this'," she said.

"It's a nice little gateway to these amazing things that the natural world does, some of which we can predict with a lot of accuracy," Schmidt said.

Wearing a T-shirt that says "I survived the cicada invasion and all I got was this shirt (and some earplugs)" that she won for posing a cicada on a toy skateboard, retiree Cindy Harris of Springfield walked through the Lincoln Garden pointing out cicadas.

"I don't know why I'm fascinated by them," Harris said.

They're just weird, with powerful jaws and jets of urine and a zombie fungus that sometimes hits them.

Cicada fascinationJennifer Rydzewski, an insect ecologist at DuPage County Forest Preserve, donned a cicada hoody costume — complete with bulging red eyes made by a 3D printer — that she wore in an educational social media post and joined a cicada walking tour.

For her video bug gig, she studied how the bugs move.

"You'd go outside and the sidewalks are just covered in them, all of them marching in the night," she said of the still wingless nymphs.

"They're very hunchbacked, just kind of slowly, almost alien-like to me, crawling with all their little appendages," Rydzewski said. But she adds, "they look really cute."

Lily Tolley, a 6-year-old in Springfield, can't get enough of the cicadas. She even feeds them to her pet lizard, Dart. When one came near her front door, she rushed over to her doorbell camera and introduced it, up close and personal. She can tell the difference between the mute females and noisy males, what the cicada parts are and how it feels "a little prickly" when a cicada walks on you. Don't worry, she quickly adds, it doesn't hurt.

Yet many people are scared or grossed out by the trillions of flying bugs that die soon after mating in a rather pungent pile on the ground.

"Creepy crawly animals is probably the most common fear that people have," said Martin Antony, chair of the psychology department at Toronto Metropolitan University and director of its anxiety research and treatment lab.

Long ago, people had to be alert to danger, so there's an evolutionary reason, he said.

"There's nothing dangerous about cicadas but cicadas may share features with other animals that are potentially threatening or carry disease," Antony said.

Helpful, not harmfulThe only possible danger is to young trees, mostly from when the females slit notches in branches to lay their eggs, Rydzewski said. So many newly planted trees sport white protective netting — a contrast to the black winged bugs lined up on some adult trees.

Overall, cicadas play an important role in the local ecosystem as fertilizer, aerating the soil and food for birds and other animals, said Marvin Lo, a tree root biologist at the Morton Arboretum. He picked up cicada carcasses from one area, ground them in his lab into a stinky powder to measure and test them later.

The arboretum was full of cicadas, cicada-peepers and scientists looking at the bugs. The critters didn't disappoint. They were there in force and weirdness. The Associated Press found a blue-eyed cicada — a one-in-a-million find.

Kritsky also found his first blue-eyed cicada in Ryerson woods. It's a numbers game. Even if they are one-in-a-million, a small plot of land will have a few because there are so many cicadas. The biologist who has written a book on this dual emergence, said the cicada invasion is dying down, but he's still looking for more.

"In about another two weeks it'll be noticeably over," Kritsky said. "It's been a blast."