As the third graders of Cumberland Elementary in the Chicago suburbs colored, clipped and glued paper to make cicadas with filmy wings, they confided their fears about what is about to happen in Illinois.

“Some people think cicadas can suck your brains out,” said Willa, a red-haired 8-year-old in a Star Wars T-shirt.

“They’re going to be so loud,” Christopher, 9, said as he colored his cicada intently. “I hate noise.”

“It’s kind of scary,” Madison, 8, said while picking through markers scattered on a green table. “What if they do something to me?”

Not to worry, Madison and Willa: Cicadas don’t actually bite, and they prefer to suck tree sap. (And Christopher, earplugs might come in handy.)

Illinois is the center of the cicada emergence in the United States, the only state that will experience cicadas nearly everywhere and see two adjacent broods — Brood XIX, or the Great Southern Brood, and Brood XIII, or the Northern Illinois Brood — come up from the soil at once. The dual emergence of the two groups of cicadas is happening for the first time since 1803, and expected to last about six weeks.

Any day now, scientists estimate, the state will be a carpet of buzzing, crawling, red-eyed insects.

“What’s special about these two broods is that they cover almost the entirety of the state of Illinois,” said Allen Lawrance, associate curator of entomology at the Peggy Notebaert Nature Museum in Chicago. “So for us in Illinois, you won’t be able to get away from them.”

Cicada mania is spreading around the state. Cicada fans are excitedly making plans to camp, hike or just enjoy the insects in their own backyards. Out-of-state visitors are driving or flying in from places where there will be fewer cicadas, or none at all. A cicada-themed public art project in Chicago will festoon the city with hundreds of ornate bug replicas.

And schools are preparing their students for the cicada emergence, hoping that education will both ease anxieties and wrap in a real-world entomology lesson.

“I’m trying to desensitize them a little bit,” said Jelena Todorovich, the art teacher at Cumberland, which is planning a schoolwide “Cicada Parade-A.” “It’s going to be real.”

People unnerved by the idea of a trillion cicadas crawling around half the country, covering lawns and driveways and crunching underfoot, may find the coming weeks revolting. But there is also fascination and delight, a fervor that carries an echo of the recent solar eclipse, which drew the attention of millions of Americans who stood in awe of a rare natural phenomenon.

“People say, ‘It’s a plague, it’s terrifying, they get in my hair,’” said Roger McMullan, who has written a graphic novel titled “Cicadapocalypse” and plans to fly to Illinois for the emergence. “But they don’t bite, they don’t sting, they’re not poisonous or venomous. They’re just these sweet little guys who hang out and suck tree sap.”

The cicada is no ordinary bug, say its biggest fans. It evokes nostalgia, they say, a soothing sound of summer, bringing a calm that borders on spiritual.

Nina Salem, the founder of the Insect Asylum, a small museum in the Avondale neighborhood of Chicago that is making plaster cicadas in its basement, said that on the eve of the emergence, she had been mulling the cicada’s life, which is mostly spent underground.

Once the cicadas use their forelegs to tunnel out from the earth, they molt and then mate, the male cicadas making the familiar buzzing sound that can be overwhelmingly loud when it is at its peak. After mating, female cicadas make slits in tree branches and lay their eggs there. The eggs hatch, and tiny nymphs burrow into the soil, beginning the process over again.

Most of the time, the adult cicadas die after only a few weeks of experiencing life above ground, their bodies falling close to where they emerged.

“They spend their entire lives waiting for this one moment to be seen and heard and felt and experienced, and then we get to do that with them,” Ms. Salem said. “It’s so fleeting. It’s just really special. And then we get to walk around and pick them up like little treasures.”

Erica Kain, a German teacher in Sewickley, Pa., has booked plane tickets to Chicago in mid-May for herself and her teenage daughters, Caroline and Genevieve.

The girls spent much of their childhood in California, where they did not see cicadas, she said. But in 2016, on a drive in eastern Ohio, a cicada brood had recently emerged. The bugs were absolutely everywhere, she recalled.

“They were splatting against the windshield — it was so loud,” Ms. Kain said. “The girls had never experienced cicadas of any sort before. We all just loved it.”

On their planned family trip to Illinois this month, they intend to drive to central Illinois, to the place where the two cicada broods will nearly overlap — “a little locust Mason-Dixon line,” as Ms. Kain called it.

She cannot wait to get out of the car and let the sound of the cicadas envelop her.

“It reminds me of when you go to the symphony and you experience the vibrations of the instruments in the room, this high-pitched roar,” Ms. Kain said. “It’s like walking into an insect nightclub.”

When the cicadas will emerge from the ground is the subject of feverish online speculation.

Some cicada fans have taken to pushing meat thermometers into their backyard soil, waiting for the temperature to reach 64 degrees Fahrenheit at about six inches deep. Once that happens, the cicadas are expected to come out.

That fact has left some Illinois residents apprehensive.

A cicada brood that emerged when Trayce Zimmermann, a publicist in Chicago, was a child in the suburbs has haunted her ever since.

She remembers standing outside her house, gazing at the dark, slightly shifting layer of cicadas that covered the sidewalk. Some of the cicadas were alive, but many of them were dead and motionless, their red eyes large and vacant, Ms. Zimmermann recounted.

She and her younger brother, Jeff, were holding brooms, assigned to clean the sidewalk by sweeping the cicadas onto the grass.

“It was like snow, covering everything,” she said. “But it was bugs.”

Though she isn’t worried about many cicadas in West Town, her neighborhood near downtown Chicago, she visits her childhood home several times a week to care for her mother. There, she has already seen holes in the dirt near large, mature trees, a sure sign that cicadas are coming.

As a way of managing her cicada anxiety, Ms. Zimmermann has created T-shirts, replacing the four stars in the Chicago flag with cicadas.

At Cumberland Elementary in Des Plaines, cicada art has already been pasted up in the hallways, and every class in the school has received a cicada education.

Lynora Jensen, a master naturalist whose daughter teaches fourth grade at Cumberland, has been a regular presence at school, gently trying to calm worries and help the students get into the cicada spirit.

“For me, it’s unacceptable to be afraid,” she said. “Education helps them to not be afraid, and to be curious. We want to get the kids feeling good about it.”

Willa, one of the third graders at Cumberland, said she had heard a lot of students talk about how scary the cicadas can be. She has tried to spread the word that they’re friendly.

“They’re only bugs,” she said.