Masters of worm grunting vibrate like moles to harvest bait

The power of 'worm charming' remained a mystery—until a biologist took a page out of Darwin's book.
One of the world's last worm grunters catches earthworms in Florida.
Gary Revell is among the world's best worm grunters, which is a dying, and somewhat mysterious, art. Ken Catania/National Science Foundation

Hours before the sun rises, the ground in Sopchoppy, Florida, begins to shake. It isn’t an earthquake. It isn’t construction. It’s Gary Revell mimicking the movement of moles.

“When people see what I do for the first time, they say it must be magic,” Revell says.

Magic doesn’t seem like a stretch when hundreds of earthworms are suddenly charmed out of the soft north Floridian dirt. Gary and his wife Audrey are Wakulla County’s most famous, and now only, professional worm grunters. At five in the morning, the Revells trek to Apalachicola National Forest every day, ready to catch buckets of bait.

“There ain’t nothing like it. When you see the daylight start cracking through the gray, the whole world starts to wake up,” Gary says.

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Tucked away in the Florida Panhandle, Apalachicola is of the most biodiverse places in the entire US and also one of the most at risk for biodiversity loss. Between the longleaf pines and the limestone-lined clay and silt soils, animals are wriggling around: the native earthworm Diplocardia mississippiensis and the hungry eastern American moles that burrow after them. 

But when the Revells head out to the forest each morning, wooden stob and rooping iron in tow, a new predator enters the woods: worm grunters. These two tools, the stob and iron, are the keys to their craft. The stob, which is a short wooden stake, is driven into the ground. Then a rooping iron, which is a heavy piece of metal that the grunter throws their weight into, is rhythmically rubbed over the stob. This causes the moist forest soil to vibrate and perturbs the worms.

Diagrams of worm grunting tools and descriptions of how they should be used next to a photo of Audrey Revell in the field
Pages from Audrey and Gary’s pamphlet, The Art of Earth Worming. Courtesy of Audrey and Gary Revell

Whether by the name of worm grunting, charming, or rooping, the idea is essentially the same: make the ground shake and wait for the worms to inch their way out. The origins of the practice aren’t clear, but Vanderbilt University biology professor Ken Catania thinks it could have been an accident; someone probably created vibrations while cutting down a tree and realized that worms responded, he says. Worm grunting has been practiced around the world for many decades, and reached a peak in Sopchoppy in the 1960s and ’70s before the US Forest Service limited it to permit holders.

Still, no one was really sure why the worms came, just that they did. Before Catania drove down to Apalachicola, the prevailing thought was that worms surfaced in response to grunting because it mimicked the rain. But he had a different idea. 

“The mother of all moles”

“It has often been said that if the ground is beaten or otherwise made to tremble, worms believe that they are pursued by a mole and leave their burrows,” naturalist Charles Darwin wrote in a book about the wrigglers. That’s what inspired Catania to find the Revells and learn if their charms could really be based on the evolution of worms and moles as predator and prey.

“I was driving down from Nashville, and the very first question was ‘are there moles down there?’” Catania says. And there were. “I started driving around on the Apalachicola National Forest roads, and there were mole tunnels crisscrossing all over the place.”

The first step was to test the rain hypothesis. Catania gathered hundreds of worms from the forest, put them in a bin, and waited for a storm to hit. The result: Only a few worms emerged, which is nothing compared to the hundreds the Revells harvest every day. Catania looked outside the bin, too, and at the actual forest. He didn’t find any critters surfacing there either. 

“Then I also recorded digging moles [with a geophone], and discovered that there’s a really good overlap between the frequencies in the ground that the worm grunters are making and that the moles are making,” Catania says.  

A worm grunter holding a pile of long pink earthworms
Revell shows off a good daily harvest. Ken Catania/National Science Foundation

Although humans don’t feel mole vibrations as much as worm grunting ones are, they can still hear the mammals on the hunt, Catania says. When he observed moles digging into the earth, worms began to pop out of the ground just like when the Revells were grunting. Coming to the surface may leave the invertebrates vulnerable to other predators, but it’s their best chance for escaping moles, Catania explains. “A mole won’t chase an earthworm out of the ground. It’s a reclusive animal with big shovel-like four limbs, and is like a fish out of water when you bring it out of the soil. It’s not a great mover out of the soil, and it’s got plenty of its own predators. It’s very rare for moles to come out.” 

But in a hypothetical battle between Gary and Audrey and two moles, the Revells would be crowned the winners, Catania says. He studied the distance between moles and where worms would emerge, as well as the difference between where the stob was placed in the ground and where worms would emerge. With the moles, worms surfaced about 10 inches away, a “pretty local response,” Catania says. But when the Revells grunted, worms surfaced more than 30 feet away in all directions. 

The Revells might be the world’s most famous grunters, but they aren’t the only ones charming worms in the forest. Animals like turtles and gulls have learned to make similar vibrations by stomping to draw out the wrigglers. Still, “the worm grunter is the mother of all moles,” Catania says. He published his findings in 2008, and consequently revolutionized the way Sopchoppy, and the world, understand grunting.

Worm gruntin' poster with a man using worm gruntin' tools on a forest floor. Illustrated in earth-tone colors.
Art made for the annual Worm Gruntin’ Festival in Sopchoppy, Florida. Courtesy of the Sopchoppy Preservation and Improvement Association 

A disappearing act

Since he was five years old, Gary has been producing mole-like vibrations to catch fleeing earthworms under the canopy of Sopchoppy’s pine and palm-laden woods. “By the time I was in sixth grade, it became a business. I started selling worms to my uncles’ bait shops,” he says.

A little over a decade later, in 1970, the Revells got married. Audrey picked up the trade, and together they became city’s official Worm Gruntin’ king and queen. “We didn’t have any money when we decided to get married, but Gary looked at me and said, ‘I know how we can get some,’” Audrey says.

That’s when things took off. Gary moved from being a worm harvester to managing all aspects of the business. He knew the buyers and the process, so he started loading worms on Greyhound buses to reach people across the state, throughout the Southeast, and even as far as Illinois.

But business has died down since. The Forest Service’s use of herbicides has made finding worms on public lands more complicated. What’s more, many people aren’t up for the early wake-up call just to drive upwards of 40 minutes and then hike into the dark woods, Gary says.

“What Gary does, it’s a dying art,” says Cindy Melzer, president of the Sopchoppy Preservation and Improvement Association, which hosts the annual Worm Gruntin’ Festival to educate the world about the dwindling practice.

Now the Revells find themselves grunting in areas they never thought about before, trying to catch their usual daily quota of 500 worms. Instead of healthy brown worms, they often find what they call “milk bait,” which hardly survive a day. Instead of Greyhound buses, a few trusted buyers will come to their bait shop to pick up a bucket of 100 worms for eight dollars. And instead of live bait, many anglers have switched to artificial lures. 

As worms get harder to find, the Revells have downsized their operation. “In the winter, the worms aren’t too active. But in the summer, they aren’t too active now either,” Gary says with a big laugh.

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The Revells have tried moving out of town for a change of scenery, but have never made it more than three months before coming back. To them, Sopchoppy is and will always be their home, no matter the number of worms in the dirt. Even while his profession dwindles, Gary says he finds himself thankful for the happiness that worm grunting in the mosquito-ridden, humid Florida forests gives him. 

“It ain’t been good all the time, but as long as you work hard and be honest, life seems to be real good and simple,” Gary says. “That’s all we want. I know I’m not a rich man, but I’ve got a lot of treasures other people don’t. The weather might change, but we ain’t.”