Everything you need to know about the periodical cicada, plus Chattanooga's evolution since the last emergence

Getty Images / Cicadas don't bite or sting, nor are they poisonous.
Getty Images / Cicadas don't bite or sting, nor are they poisonous.

Editor's note: By the time you read this, our mass emergence of spring cicadas may have already come and gone. The boisterous phenomenon lasts only a month or so, and there's no telling when they'll emerge or even how many there may be. As conspicuous as they are, periodical cicadas are mysterious creatures - which is part of what makes them indefinitely interesting.

Seventeen years ago, a female cicada climbed a hickory tree in Ocoee, Tennessee. Using the knife-like appendage attached to her abdomen, she made cuts in the underside of branches and filled them with eggs, hundreds and hundreds of them.

Six weeks later, her squirmy nymphs hatched, alongside millions of others in nearby trees. Collectively, they dropped to the soil and began to burrow in search of roots, their food source.

While that was happening, I was 20 years old. It was 2004. Myspace was just getting started. Smartphones didn't exist. Even texting wasn't a thing yet.

I was studying business at a community college just outside my hometown of Versailles, Kentucky, a major I'd chosen after an advisor told me that creative writing wasn't a practical career path. I would go on to graduate with a marketing degree, and over the following years I would work various jobs - housekeeper; ESL instructor; legal assistant.

Five years after graduation, I was spending my days alone in a windowless cubicle, mindlessly reviewing medical records and dreaming of new adventures.

On slow days, to pass the time, I wrote stories about my co-workers, inspired by conversations I overheard at the copier or awkward encounters I'd had in the elevator. Once, I accidentally sent one to the community printer and a co-worker found it.

It was the talk of the lunch room for a week - which I could hear from behind my gray partition walls where I burned with embarrassment, longing to crawl out of my skin.

Meanwhile, the cicadas were doing just that.

Throughout their life underground, a cicada molts five times. With each, it becomes larger, transforming from a tiny termite-like insect into a plump red one. Known as instars, each stage lasts an average of four years, except for the first, the shortest - making cicadas a long-awaited yet cyclical phenomenon.

Around the time the nymphs were reaching their last full stage underground, I had begun reading my stories at open mic nights. A couple of local zines offered to publish my work. I built a small portfolio and applied to creative writing graduate programs in cities I'd never visited.

When that didn't work out, desperate for change, I began emailing my portfolio to magazine editors across the country, asking for a job.

In 2013, at age 28, I was offered a position with Get Out and moved to Chattanooga.

Over the past eight years, I've transformed in ways I never imagined. My work connected me to an outdoor culture that had previously been out of reach. I learned the names of birds, plants and insects. I began running and paddling. I became an editor, my passion taking root.

Three years ago, while covering a local paddling festival, I met a man who would become my fiancé. Last year, we moved to Ocoee and built a cabin. Our yard is edged with oaks, maples and hickories - favorites among cicadas.

Just 18 inches beneath my feet, they are finally beginning to burrow upward.

In late spring, the cicadas will emerge en masse - billions of them, across 18 states - in one of nature's most extraordinary events. Above ground, they will molt once more, shedding their soft nymph shells and sprouting wings.

Then, they will return to the branches in which they hatched. And, at long last, they'll sing.

***

Here, local outdoorspeople reflect on how their lives and the city has changed since the last cicada emergence 17 years ago.

THE BIRTH OF AN OUTDOOR CULTURE

"In 2004, Bob Corker was mayor of Chattanooga," remembers Dawson Wheeler, co-founder of Rock/Creek Outfitters and host of the adventure-storytelling Day Fire Podcast.

"It was during this time that Bob planted the flag with the famous statement, 'Chattanooga is the Boulder (Colorado) of the East.'

"This truly was a bold statement. Plans and rally cries rang out to all outdoor partners, foundations, enthusiasts, the city itself and the county government ... The culture of our outdoor community was born.

"Today, we witness the blossoming of Enterprise South Park, 5-Points (mountain bike trails), the Riverwalk sections, over 140 miles of mountain bike trails, new bouldering and climbing areas, and the list goes on. [Chattanooga's] events, such as StumpJump, Ironman, Head of the Hooch, Chattajack, Triple Crown Bouldering and Chattanooga Waterfront Triathlon are some of our signature competitions.

"We have made much progress with our outdoor recreational resources and events, but there is much work to do in fair and equitable use, sustainability and barriers to entry."

A SUMMER OF ABUNDANCE

Tish Gailmard vividly recalls the 2004 cicada emergence.

"[Reflection Riding Arboretum and Nature Center] was covered up with them," says Gailmard, who began her career at the nature center as an animal caregiver in 2000. "You couldn't drive your car without hearing 'crunch,' 'crunch,' 'crunch.' Their skins were stuck all over the trees and shrubs. I spent the summer picking up cicadas to feed to our opossum, crow and broad-winged hawk.

At that time, "Our [three] children were elementary-, middle- and high school-aged and often accompanied me to work," she adds. "My daughter, now 26, still remembers the loudness of the cicadas."

But the insects weren't the only thing in abundance at the nature center that year. The privet was, too, Gailmard remembers.

"It was so bad that when you pulled into the parking lot, you couldn't see through the woods because of it all, "Gailmard says. "That's a big difference now. This year, we did about 20 acres of privet removal."

photo Getty Images / A Brood X cicada is seen in 2004.

THE LONG GAME

"In 2004, I was the mother of girls ages 5 and 9 and was working in corporate America," says Robyn Carlton, CEO of Lookout Mountain Conservancy. "When I was my daughter's age, I had discovered the great outdoors and it had become my safe haven. One of the many things I wanted for my girls was for them to find that special place outdoors that makes their heart sing."

Four years later, Carlton led by example, leaving her career in health care to begin work with the local land conservancy, dedicating her time to helping preserve the city's natural landscape for future generations.

"As I think about the awakening of the cicadas, I think about how long I've waited for things. As we all emerge, may the patience and the persistence of a cicada be within us."

THE CYCLE OF LIFE

"In 2004 I was fresh out of college, putting my hard-earned sociology degree to use as a raft guide on the Ocoee River," says Schandra "Sunshine" Loveless, now customer relations specialist for Outdoor Chattanooga. "That was the same year I started playing full-contact football with the Chattanooga Locomotion."

The following years were a whirlwind for Loveless. She played for Team USA in the first International Federation of American Football Women's World Championship, and won a gold medal. She retired her cleats after an injury and began to mountain bike. She beat cancer.

In 2018, "After 17 years of guiding on the Ocoee, I decided it was time to trade the whitewater for flatwater, and founded Sunshine's Adventures, a paddleboard touring company.

"On a final note, and somber yet symbolic coincidence to the timing of the cicada," Loveless says, "I'm writing this as I return from California after attending my maternal grandmother's funeral. I made the same trip for my maternal grandfather's funeral 17 years earlier in 2004. Death and birth. The cycle of life."

PROGRESS MARCHES ON

"Seventeen years ago, I never could have dreamed of calling my friends in the Caribbean on WhatsApp for free to check on them after a hurricane or volcanic explosion," says Mary Beth Sutton, who founded the clean-water advocacy project CaribbeanSEA in 2004.

That year, she says, "My kids were in elementary and middle school. I got the opportunity to start this nonprofit with a focus on Caribbean communities. I mostly didn't get paid.

"I took my kids with me when I was working in the Caribbean. They learned people are people wherever you are, no matter the culture or color or your skin. Friends are everywhere!"

In 2012, Sutton opened The Gear Closet, a sporting goods resale shop, to help support her clean-water initiatives. In 2019, she rebranded as WaterWays to more accurately reflect her work, which includes watershed restoration in Southeast Tennessee as well as the Caribbean.

"Seventeen years ago," Sutton says, "I couldn't have imagined connecting with folks around the world on Zoom. I couldn't have imagined the miracle of science providing me a new lease on life through a stem cell transplant, or the world combating a viral pandemic through an mRNA vaccine. There is so much good going on. Let's hope the cicadas cheer us on to even better actions!"

A NEW GENERATION BEGINS

"In 2004, I was serving the community as the morning meteorologist at WRCB-TV," says Thom Benson, who has now spent the past 15 years as the Tennessee Aquarium's communications manager. "I was also doing quite a bit of reporting in '04.

"Among the memorable stories I produced was coverage of the Tennessee Aquarium's construction of the Ocean Journey building and work on the 21st Century Waterfront. Both opened in 2005 along with Hunter Museum's expansion."

But now, "17 years later, I'm thinking about my two granddaughters, ages 4 and 8," he says. "Time spent outdoors with them allows me to see the world differently, through their eyes. Fortunately they absolutely love being outside, so whenever we're out I try to teach them about wildlife and exploring nature with all of our senses.

"So if you were to ask me if 2021 is better than 2004, I would say, 'Absolutely.' And, I hope the next time the cicadas emerge in 2038, [my granddaughters] will invite Papa for a walk in the woods to listen to them."

***

The periodical cicada is a fascinating phenomenon – and a largely mysterious one. Here, we burrow into what is known and unknown about the insect.

What is a periodical cicada?

Cicadas are classified as a "superfamily," which is biology's way of saying, "It's complicated."

To help identify a periodical and the specific ones now emerging, let's break it down:

There are 3,000 species of cicada in the world, all belonging to one of two categories: annuals or periodicals.

Annual cicadas emerge every spring, while periodicals emerge once every 13 or 17 years. Among periodicals, these two life cycles represent two distinct races: the 13-year, more common in the Southern U.S., and the 17-year, more common in the north.

Tennessee, however, has both.

This year, the latter will emerge - more specifically, Brood X, which is the name given to this particular generation of periodicals. According to entomologists, this brood is considered one of the largest, with estimates of up to 1.5 million cicadas per acre.

Still, some experts, including Hamilton County extension agent Tom Stebbins, believe that the 13-years' Brood XIX, expected to emerge in Tennessee in 2024, will be even larger.

Why the prime numbers?

Cicadas don't bite or sting, nor are they poisonous, which makes them rather vulnerable to the many animals that eat them, from birds to lizards to rodents and beyond.

So, to ensure the survival of its species, the periodical adapted two clever tactics.

First, safety in numbers. Cicadas' sheer abundance ensures they won't all be consumed, a strategy known as "predator satiation."

Second, and even more ingenious, is their prime-numbered life cycles. The idea is that by emerging once every 13 or 17 years, cicadas prevent predators from matching their reproductive schedules.

For instance, if periodicals had a more sensible cycle, an insect-loving bird could co-evolve alongside it, hatching larger clutches during years of abundance.

As an article by Nature Education further explains, "a 12-year cicada species could be wiped out by a predator species with a 2-, 3-, 4- or 6-year life cycle because each cicada emergence would be met with a boom in the predator population."

However, all that is just a theory. Why cicadas adapted these lengthy, prime-numbered life cycles is largely a mystery. While they may make it difficult for predators, they also make it difficult for science.

The other burning mysteries

Similarly, why periodicals spend so long underground or how, exactly, they know it's time to emerge are questions without definitive answers.

But, again, there are some good theories.

Many believe that their long-lasting nymph-hood may be linked to the last ice age. Because cicadas prefer warmer weather - waiting, each spring, for the ground to reach around 65 degrees F before emerging - the cool climate 20,000 years ago may have delayed their development, setting them on a continued drawn-out life cycle.

In regards to a cicada's ability to keep track of time, the leading hypothesis suggests that cicadas use an internal molecular clock, calibrated by the environment. Each spring, the trees bud, sending a message to the nymphs via the trees' roots. After accumulating a respective number of these messages - 13 or 17 - the cicadas wait for the ground to warm, then tunnel to the surface.

A glitch in the matrix

In 2002, the University of California tested the "molecular clock with environmental cues" theory.

Researchers started with peach trees that were supporting 17-year cicada nymphs, which had already been underground for 15 years. Then, they manipulated the trees, causing them to bloom twice in a year.

Sure enough, the cicadas emerged a year early, thus indicating that cicadas track time by counting their hosts' season cycles.

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