Hordes of thunderous, harmless cicadas are coming. It's normal to feel a little dread.

A once-in-a-lifetime emergence of cicadas will hit the U.S. this spring, bringing a fascinating, excruciatingly loud and strangely unsettling experience for millions of Americans.

Cicadas are loud — loud enough to theoretically hurt your hearing in the right circumstances. And experts say swarms of bugs can cause understandable stress for many people, especially as billions or trillions of the creatures emerge from the ground.

Katherine Brownlowe, a psychiatrist at the Ohio State University Wexner Medical Center, said cicadas can evoke anxieties, particularly for people with sensory overload sensitivities, a phobia of cicadas or an anxiety disorder for a few reasons.

"There is kind of a discomfort or disgust feeling that's common for most humans around most bugs, Brownlowe said. "The discomfort we can have is almost evolutionary."

The noise is also a legitimate nuisance. Floyd Shockley, co-leader of the Entomology Department at the Smithsonian’s National Museum of Natural History, said spending long periods of time around the bugs without hearing protection can be "painful."

Experts say the bugs aren't dangerous, but the noise and anxiety they can create are real concerns for some people. Here's what to know:

What's happening with cicadas in spring 2024?

Two different groups, or broods, of cicadas, are expected to emerge in the Southeast and Midwest beginning in mid-May and lasting through late June. Brood XIX is expected to emerge in 14 states – including Alabama, Arkansas and Georgia. Brood XIII is expected in the Midwestern states of Illinois, Indiana, Iowa and Wisconsin.

Despite the the noise they produce, the critters are not otherwise harmful to humans and can provide environmental benefits, including a food source for birds, according to the U.S. Environmental Protection Agency.

A bit of anxiety about the cicadas is normal

It's normal to feel a little anxious or uneasy as the noise ramps up and huge numbers of unfamiliar big bugs appear, Brownlowe said.

"But Americans largely shouldn't be afraid," she said.

Meanwhile, people who experience sensory sensitives and live in areas where the cicadas will emerge are likely to feel more anxious about the noise from the critters than people without them — and for legitimate reason, said Zoe Gross, a director of advocacy at the national nonprofit organization Autistic Self Advocacy Network.

Noise from the cicadas will be noticeable for those people, including autistic people, she said.

"It’s much more magnified to you than it might be to someone without this disability," Gross said.

And people who have difficulty with change will experience a double whammy, with the added noise and an unfamiliar environment when the seasons change, she said.

Are cicadas loud enough to hurt your hearing?

Kind of.

They make a buzzing noise that can be as loud as a lawnmower. But only those who are exposed to large groups of the bugs for longer than 10 or 15 minutes could experience temporary hearing impairments, said Thomas Powers, who lives in New Jersey and provides management consulting to companies within the hearing health industry as the founder of Powers Consulting.

The Occupational Safety and Health Administration's legal limit for noise level in the workplace is 90 decibels over the course of eight hours, an average workday in the U.S.

Cicadas in large groups can get up to 100 decibels, Powers said. But it's unlikely the average American will get close enough to them or stay near them long enough to experience any sort of hearing loss.

"By the time you get up to about 100 decibels, you shouldn’t be in that environment for more than 15 minutes," Powers said. "If I think back to cicadas here, well, they’re interesting, but I'm not sure I want to stay up there for 6 to 8 hours listening to them."

In areas where a large number of cicadas have emerged and the males are all singing at the same time the sound can be “impressive,” said Shockley.

“To the point that I’ve been in an area where I had to put earplugs in because they were so loud and so abundant that it was painful,” he said.

What can people do about the noise?

There are ways to tune out the fears before they become limiting to one's everyday life, Brownlowe said.

Experts said best practices include:

• Exposure therapy: Spending time outside around the bugs can make the experience less uneasy, Brownlowe said.
• Thinking of the sounds cicadas exude as white noise.
• Playing white noise or music in the background to distract from the noise of cicadas.
• Wearing earplugs or headphones to lower the noise level.
• Reading a social story, which is a scenario depicted in photos that can prepare people for an unfamiliar situation.

Cicadas 2024:2 broods to emerge together in US for first time in over 200 years

Contact Kayla Jimenez at kjimenez@usatoday.com. Follow her on X, formerly Twitter, at @kaylajjimenez.