What is worm grunting? Learn how to get worms out of the ground with a grunting stick and the power of vibrations.
When people started summoning worms to the surface of the soil with vibrations, it was probably confused with sorcery or witchcraft. That’s even what it sounds like when you describe it: “First, you’ll pound a wooden stake in the ground, then you’ll take this wand, and then worms will start coming up from the ground like they’re running from the lord of the underworld.” Even today, I feel like I’m explaining unusual religious rites when I tell a friend about worm grunting.
What is Worm Grunting?
They call it “grunting” because that’s what it sounds like – a critter making grunting noises. To add to the already full pile of improbabilities, the grunting noises actually do sound like a critter to the worms, but not what humans might imagine. When worm grunters run their “rooping iron” (a long, thick, flat-ish metal slab) over a “stob,” a stake in the ground, it sounds to our ears like the noise a hog might make, but to worms, it’s hypothesized to sound like the digging noises of a mole that’s hot on their tails. This is their cue to book it to the surface and risk the devil they don’t know in lieu of the devil (they think) they do. Some people also call worm grunting “snoring,” because the frequency and cadence make it sound like your dad is napping where someone is trying to get fishing bait or populate their vermicompost bin.
The timing for snoring isn’t too far off, though, since the best window to get worms is just before sunup. Experienced grunters also seek out low ground that has a better chance of being saturated with moisture. Perhaps the moist ground is just where the worms are already close to the surface, or maybe the moisture content of the soil makes the vibrations carry better. A 2008 Vanderbilt University study showed that those vibrations could draw worms up from a 12-meter radius, provided strong evidence for the hypothesis that the worms believe they’re fleeing a mole, and pretty much debunked the conjecture that the vibrations mimic the sound of rain droplets hitting the surface.
So how, precisely, do the experts summon the worms?
How to Get Worms Out of the Ground
Experienced grunters kneel by the stob, nearly straddling it, and saw the iron over the top of it with one hand at each end of the iron and shoulders directly over the stob, like a medic using good form to perform CPR. They’ll also readjust the depth of the stob if it isn’t tight enough in the ground. A loose stob or a too-long stob won’t vibrate at the right frog-croak frequency. People who are good at this tend to use a big stake for the stob, roughly 2 inches in diameter, with a fairly long taper to the point. Too blunt not only makes the stob hard to pound into the ground, but also doesn’t keep it in tight contact with the ground, which is critical for both the creation of vibrations and their transmission to the intended audience. Depending on the wood, the stob’s top may need to be beveled or rounded to keep the corners from peeling off during grunting. Experts prefer medium-hard woods for stobs.
The rooping iron, like an oversized file without teeth, can be purpose-made, but a repurposed automotive leaf spring will do in a pinch. When grunters run the iron over the stob, they’ll do it at such an angle that the iron catches and then releases the stob over and over again, like when you make a wine glass “sing” by running a wet finger around its lip, but at a lower frequency. The iron requires a certain amount of mass to smoothly carry the motion of the long, flat surface over the top of the stob without stopping, despite the hiccups that make the signature noise. This is why purpose-built stobs tend to be thick (1/2 inch or more), fairly wide (3 inches or more), around 2 feet long, and made of steel. A large farrier’s rasp with ground-off teeth will also do the trick.
Worm Fiddling
In addition to snoring and calling, worm grunting is also called “fiddling” because of an alternate technique where you make vibrations by pulling a stick across the stob. Run a normal stick up and down the notches of a stob, or put the notches in a stick and run it over the stob like you’re playing the fiddle. I don’t see the pros of fiddling, and I’ve never had any luck with it myself, but the technique has probably got a name for a reason.
When fiddling, it’s tempting to saw on the stob as fast as you can, because you may think more is always better, and the technique doesn’t demand any breaks for resetting like grunting does. However, in the geophone recordings of moles from the 2008 study, the creatures have an organic, irregular rhythm to their digging. The timing reminded me a lot of the video of worm grunter original Gary Revell doing his thing in front of a crowd: grunt, pause, grunt, grunt, pause. It makes me wonder if tempo isn’t just as important as volume and tone when doing this magic trick.
Grounded in History
Worm calling isn’t new. In 1881, Charles Darwin observed: “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.” Before Darwin, herring gulls were paddling the ground with their feet like they were speed training for a jump-rope competition, prompting worms to surface in front of them. Wood turtles have also been doing it to satisfy their cravings for munchies since time immemorial, but instead of the gulls’ DanceFit routine, the turtles execute their version of a pushup and then body-slam (insomuch as a turtle is able to body-slam) the ground as they’re stomping around.
In the 1960s, grunting and the sale of worms became a cottage industry in the Southeast, particularly in and around Florida’s Apalachicola National Forest, where its native earthworms, Diplocardia mississippiensis, are both enormous and particularly prone to skedaddling in the presence of vibrations.
When money is involved, things always get weird. People started using chainsaws and power tools to get bigger yields with inorganic vibrations. In 1972, “CBS News” aired a story about worm grunting, and people started asking questions about the income generated and how worms were being harvested. Those power-tool techniques have long since been banned for the collection of worms in the Apalachicola National Forest, but some time-honored traditions and deep-rooted expertise have remained. The annual Sopchoppy Worm Gruntin’ Festival in the curve of the Florida boomerang is now the North American epicenter of the worm-grunting world. Worm-grunting experts Gary and Audrey Revell, who started off as Revell Live Bait, are now Florida Folk Heritage Award winners for their work promoting the craft.
Sopchoppy’s European counterpart is Willaston, England, where they hold the World Worm Charming Championships, and where technique varies quite a bit from this side of the pond. Whereas American worm callers focus on stobs and irons, Willaston worm charmers tend to do more of their work with pitchforks – either banging the handle with sticks while the tines are sunken, or prying them in the ground like a mock dig. Before you dismiss this technique, consider how many worms you’ve found while digging and how many came up in a shovelful versus how many just came out of the ground while you were shoveling. If you still have doubts, look at video footage of what worms do in advance of a mole charging into their territory. Then, consider what the earth looks like when a mole is plowing through as compared with when you loosen it up with a pitchfork.
I’ve never seen anybody try the Willaston pitchfork technique on the U.S. native D. mississippiensis, but those are different worms than the ones in England. To stoke the fire of irony even more, since most of the worms in the upper U.S. are invasive, brought by Europeans in potted plants and ship ballast, they’re probably the same as the worms in Willaston. It’s not so much that the European worms were more aggressive or less prone to disease than their North American cousins, just that their cousins had largely been wiped out. The Laurentide ice sheet plowed over most of North America during the last ice age and made it inhospitable to pretty much everything, leaving an earthworm void. Moving in and getting cozy wasn’t difficult for the European newcomers.
There’s some debate as to whether invasive worms are messing with our native forests’ ability to defend against invasive plants and store carbon, so if you can match the 2009 Willaston record of 567 worms in a 9-square-meter area, you might just be doing the forest ecosystem a favor. At the very least, you’ll have a lot of fishing bait or enough survival food for a while, even if you’re abominable at fishing.
Josh Lau is an engineer, inventor, scoutmaster, and centimarathoner. He raises steers, chickens, and fish in the middle of Oregon with his amazing family.
Originally published in the March/ April 2025 issue of Grit magazine and regularly vetted for accuracy.
