(NewsNation) — It’s been 221 years since two broods of cicadas emerged simultaneously from the Earth and took over.

But more than two centuries later, you may start seeing them in your neighborhood. Pretty soon, the males’ reproductive cry will be heard singing from the treetops as they try to attract a mate and reproduce.

One video from the St. Louis, Missouri, area shows thousands of cicadas emerging from the ground.

They’ll make their way up and into the trees, where they will shed their exoskeleton and begin the mating process before dying off.

For this year’s emergence, two cicada groups are targeting specific areas of our country, though there’s going to be some overlap in several states, too.

Brood 19 is already taking over southeast America in states like North Carolina, South Carolina, Missouri, Arkansas and Louisiana.

Brood 13 is heavily concentrated in states like Illinois, Iowa and Wisconsin.

Across America, there are differing opinions about this rare phenomenon.

Christy Buck, an Arkansas resident, called it a “once-in-a-lifetime” event akin to the recent solar eclipse.

“I love it, I love the sound of them,” Buck said. “I think it’s really neat.”

Diane Rodgers, who lives in Missouri, says she’s afraid they’ll be “dive-bombing” around her.

“I’ll be gardening, and they will be flying in my hair,” Rodgers said. I have a lot going on; I don’t need help with that.”

Once the cicadas are done emerging, we’ll be dealing with them for about six weeks, with the invasion expected to be over by July 4.

What to know during cicada season

When the cicadas come to your area, you can expect a lot of noise, said Tamra Reall, an entomologist and horticulture field specialist at the University of Missouri, on NewsNation’s “Morning in America.”

“If you’re in one of the areas where they’re emerging, they will literally cover the trees. There will be so many that you will be able to see that you can’t miss it. And it is loud,” Reall said.

Other than that, though, cicadas won’t cause humans much harm, experts say, and veterinarians say they only pose a “minimal risk” to pets since they are not toxic and don’t sting.

Exoskeletons, however, could be hard for pets to digest, which Purdue’s Department of Entomology says can give them an upset stomach. If you have any concerns after seeing a pet interact with a cicada, you should let your veterinarian know.

While some of the cicadas will be infected with a zombie-like fungus, they still don’t pose a danger. Only a low percentage are expected to even get this fungus, which is a sexually transmitted disease that ironically can make the cicadas hypersexual.

“The cicada continues to participate in normal activities like it would if it was healthy,” Matthew Kasson, an associate professor of Mycology and Forest Pathology at West Virginia University, said in an interview with CBS News. “Like it tries to mate, it flies around, it walks on plants. Yet a third of its body has been replaced by fungus. That’s really kind of bizarre.”

University of Connecticut entomologist John Cooley said he’s seen areas in the Midwest where up to 10% of cicadas were infected.

It’s a real problem that “is even stranger than science fiction,” Cooley said. This white fungus, Cooley told the Associated Press, takes over the male cicada, their gonads are torn from their body, and chalky spores are spread around to nearby to others, he said.

“They’re completely at the mercy of the fungus,” Cooley said. “They’re walking dead.”

The Associated Press contributed to this report.