Under the canopy of a regal oak, Gene Kritsky points his camera at the tree’s trunk, the lens nearly touching the bark. “Well, hello!” he says, snapping a photo of a Magicicada septendecim. Here in Cincinnati, it’s the first truly hot day of the year; the sky has been blue and cloudless all afternoon, sending the temperature soaring into the 90s. It’s also the first day of Kritsky’s field research in Mount St. Joseph Cemetery, the first time in 17 years that Magicicada is due to emerge in the area.

“Oh, it’s nice to be back,” Kritsky says, walking over to another oak. This has been one of Kritsky’s research sites for nearly 40 years; he arrived at Mount St. Joseph University (affectionately called Mount St. Joe’s by locals) as an associate professor in 1983, and now serves as dean of the university’s School of Behavioral and Natural Sciences. In those years, Kritsky has established himself as one of the world’s foremost cicada experts—and with his well-groomed white beard and tortoiseshell glasses, he looks every bit the part of the distinguished entomologist.

He crouches close to the ground, examining a series of finger-width holes in the earth; this is where cicada nymphs had surfaced as soon as the soil became warm enough. (Their trigger is a temperature around 64 degrees Fahrenheit; this year, there were reports of cicadas emerging as early as April from soil warmed by nearby hot tubs or dryer vents.) From there, the nymphs look for something, anything, to climb. On the tree in front of us, dozens of cicadas are making their way up. Kritsky points out clusters of the insects on tree leaves 20 feet above our heads. “They’re all gathering at the top, just as happy as can be,” Kritsky says. Others have climbed to as high as possible on tall grass, bushes, and even the cemetery’s headstones. There, they molt into their adult form, leaving behind brown exoskeletons. Some of these remain stuck to twigs and leaves; others fall to the ground, forming a crunchy carpet around tree trunks.

Soon, there will be billions of these shells strewn across the eastern U.S. While there are 3,300 other cicada species in the world, North American periodical cicadas steal the show when they emerge. For one, they’re hard to ignore; they emerge in such numbers that people often confuse them with locusts, and their mating calls can reach upwards of 90 decibels, as loud as a motorcycle or lawnmower. (During past emergences, cicadas have nearly drowned out speeches from the likes of Theodore Roosevelt and Bob Dylan.) And then there’s their peculiar life cycle: North American periodical cicadas spend either 13 or 17 years developing underground, sucking sap from the xylem in tree roots, and when they finally emerge, they’re alive for just a few more weeks to mate. (“To live underground for 17 years, then emerge into the light and air to love and die reminds me of a Greek tragedy, a sad fate,” wrote a commenter on the website Cicada Mania, a clearinghouse for cicada facts and research.) Broods are grouped by the year in which they emerge, and of the twelve 17-year cicada broods, the one emerging this year—Brood 10, often written as Brood X—has the widest geographical range. Spanning 15 states, Brood X emerges in major urban areas like Washington DC, Philadelphia, Cincinnati, and Indianapolis, inspiring countless social media posts (“is it ok if my dog ate 3 cicadas?”) and a wealth of news stories.

If you’ve heard the ear-splitting screams of periodical cicadas, seen an orgy of them squirming at the base of a tree, or walked through a cloud of lazy, slow-flying cicadas, it might be hard to imagine that they could be in trouble when there seem to be so many of them. Perhaps too many, if you ask some people. While some enthusiasts welcome mass cicada emergences, the general public seems eager to avoid them. When we first spoke in January, Kritsky said he’d already been fielding calls from people planning outdoor weddings or proms, asking for his advice about when to time their event to avoid the emergence. In the month before Brood X’s emergence, news stories offered tips for avoiding “the 17 year nuisances,” and shared concerns that the emergence could make outdoor dining “a total nightmare.” Cicada phobia has led to hospital visits, car accidents, and even a 1987 cicada robbery: two men threw a cicada—“which is big and ugly but harmless,” according to New London, Conn. newspaper The Day—to rattle a restaurant cashier, then stole $25 from the cash register. “If you did man on the street interviews, you’d find plenty of people who want to rain hot flaming death upon cicadas as far as you possibly could,” says John Cooley, a cicada researcher at the University of Connecticut.

In light of this anti-cicada sentiment, cicada researchers are eager to dispel myths and misconceptions about the insects. After my first email to Chris Simon, one of Cooley’s colleagues at the University of Connecticut, her reply included a document called “Magicada Media Faux Pas,” explaining why frequently used terms like “swarm,” “invasion,” and “plague,” are inaccurate in describing cicadas’ emergence. The term “overrun,” too, gives the wrong impression; Simon’s document says it “implies that they are imposing on us when in fact we are much more of an imposition on them—clearing their trees and building asphalt parking lots on top of them.”

But the tree-clearing cicada imposition began long before there was asphalt. Researchers believe modern periodical cicadas appeared right around the end of the last Ice Age, between ten and fifteen thousand years ago, and among Indigenous communities, stories featuring cicadas have been passed down since time immemorial. North American colonists made the first written observations of cicadas, but also set to work building houses, farms, and cities. In the process, they uprooted massive tracts of land across the eastern half of the continent, destroying cicada habitat as they went. Naturalists at the time had little clue what cicadas were, calling them “flies,” and they certainly had no clue or concern that they were uprooting cicadas’ homes. By all accounts, the cicadas were plentiful, perhaps too much so. One researcher sent on an expedition by the Swedish government mistook cicadas for locusts, which, he wrote, came out in “dreadful quantities.”

As deforestation and urbanization increased across the continent, it wasn’t long before cicada reports began mentioning an apparent decline. Brood XXI, a 13-year periodical cicada brood once found in Florida, disappeared after the 1870s. And during 17-year Brood XI’s emergence in 1903, Connecticut landowners told USDA entomologist Charles Marlatt about low numbers in their area and predicted that the population might disappear entirely. Unfortunately, they were right; the last known Brood XI emergence took place in Willington, Connecticut in 1954, and subsequent surveys during Brood XI years have turned up none.

Four years later, entomologist Frank Young published a paper about cicadas in the Proceedings of the Indiana Academy of Sciences. “There is no doubt that all of the broods have declined since the early settlement,” he wrote, noting that the 1953 emergence of Brood X appeared to be smaller than its 1936 emergence. Kritsky, one of Young’s students, carried on this work. In 2004, his surveys found that Brood X cicadas had disappeared from 24 counties in western Ohio and Indiana where they had been reported in the past. In general, Kritsky says, cicadas’ range seems to be growing patchier. “You could find a pocket here, and then need to go 3 miles to find more. It’s not the continuous range we used to have—it’s much more disjunctive.” Similarly, Brood VII cicadas, once plentiful across eight counties in upstate New York, are now found in only one. And a 2012 study of Brood XIII cicadas, just outside of Chicago, finds they’re also in decline.

Now, deforestation isn’t the cicadas’ only foe: Climate change could also contribute to habitat loss. The now-extinct broods have one thing in common: They are near the southern- and northern-most edges of the cicadas’ natural habitat. If climate change leads to more extreme weather—hotter summers, colder winters, bigger storms—that might make it more difficult for cicadas to survive.

Despite the evidence of decline, Brood X cicadas are still plentiful—but researchers wonder how quickly that could change. When I ask Cooley if he thinks it’s possible cicadas could go extinct, he at first approaches the question with a scientist’s caution, enumerating the limitations and flaws of the data which suggests cicadas’ decline. But after five minutes of talking through cicadas’ threats—deforestation, climate change, pesticides—it’s clear Cooley has some concerns. I ask again: Could cicadas really disappear? “My hunch is absolutely—they’re going to be like the passenger pigeons of the insect world,” he says. “It’s the kind of species people are going to say there are so many, nothing could ever harm them, and then run around cutting down the forests, spraying pesticides, and then boom, they’re gone.” Like cicadas, billions of passenger pigeons called the eastern U.S. home. In 1813, John James Audubon, writing from Kentucky, estimated he saw more than a billion literally darkening the sky, but by 1900, the last wild passenger pigeon was dead. And like cicadas, passenger pigeons relied on abundance to survive. Theoretically, once a population dwindles, it may be reduced to the point of no return, edging closer to extinction. “I suspect they’re more vulnerable than anyone would assume,” says Cooley.

Back at the cemetery, Kritsky and I finish up his first survey of the year and hop in his car, a Chevy Malibu with the license plate CICADA. As we drive back towards his office, I ask him about something that’s been on my mind. To me, it feels like cicada data will always be unsatisfyingly inconclusive. Even with thousands of citizen scientists on the ground, it’s impossible to track a brood’s full range, much less every single cicada; a definitive ruling on cicadas’ decline is elusive.

Kritsky says he’s gotten this question before. “I had people ask me a few years ago, why should Mt. St. Joe do this? Why are they willing to spend $60,000 on an app? Why do they give me the server space to do the app, to keep it going? Why is it we even care about the cicadas?”

Then, he tells me a story about a conference he spoke at a few years ago, which honored the work of Gregor Mendel using the lens of Pope Francis’s 2015 encyclical Laudato si’. The papal proclamation draws attention to climate change and biodiversity loss, the need for better research, and entreats the people of the world to “care for our common home.” Kritsky’s an avowed atheist, but I sense that his point is that it’s not just about the data itself; it’s about the effort behind the data, too. Every day, Kritsky gets emails with pictures of cicadas from citizen scientists, who may not have cared at all about these strange insects before seeing him on Kimmel or the local news. When I called one Cicada Safari user who was on the leaderboard for submissions, she told me she loathed cicadas in 2004, but after learning about them through the app, she was enamored. She could hardly wait, she said. I realized the same was true for me; the charisma of Magicicada turned my fear into fascination, and finally, respect.

Kritsky repeats my question: so, why do we care? And then he answers it: “A world without periodical cicadas is just not as nice of a home.”