How 'Worm Grunting' Works

Two contestants of the world worm charming competition call worms from a field at Willaston, Cheshire, England. © Richard Baker/In Pictures/Corbis

What manner of man is this who can summon worms from the earth with only hammers, stakes and maybe a woodwind instrument?

Depending on where you live, you may call him worm charmer, worm fiddler or worm snorer. Floridians, however, call the practice "worm grunting."

Yes, the passtime is quite established in the southeastern United States and even in the United Kingdom, which hosts the World Worm Charming Championships each year in Cheshire.

The idea is to create just the right soil vibrations to drive hundreds of fat fishing worms to the surface. In Florida, they drive a wooden stake into the ground and rub a steel "rooping iron" across the top to generate a kind of grunting noise. The English method involves everything from pitchfork percussion to dribbled tea. Heck, even non-humans get it on the fun: Wood turtles and sea gulls stomp the ground to drive their squirming dinner skyward.

The Science of Worm Grunting

Needless to say, you don't have to understand worm behavior to be a successful grunter. Some thought it was magic, others suspected the vibrations sounded like rain drops -- and we all know how heavy rains drive worms to the surface to avoid a watery death.

But according to a 2008 study from biologist Ken Catania, it all has to do with moles. Since the mole is the worm-gobbler par excellence, its prey will far rather risk dehydration, fishermen, turtles and gulls on the surface than those jaws of doom in the underground. So the grunter's sounds simply mimic the reverberations of a tunneling mole and drive the worms to the surface.

Catania explored all of this in a series of experiments (including one that ruled out the rain drop theory) and found that worm grunting vibrations were more uniform and concentrated near 80 Hz while moles produce a wider range of vibrations that peak at around 200 Hz. But there' s just enough overlap between the two to make the bizarre practice of worm grunting a reality.

About the Author: Robert Lamb spent his childhood reading books and staring into the woods — first in Newfoundland, Canada and then in rural Tennessee. There was also a long stretch in which he was terrified of alien abduction. He earned a degree in creative writing. He taught high school and then attended journalism school. He wrote for the smallest of small-town newspapers before finally becoming a full-time science writer and podcaster. He’s currently a senior writer at HowStuffWorks and has co-hosted the science podcast Stuff to Blow Your Mind since its inception in 2010. In his spare time, he enjoys traveling with his wife Bonnie, discussing dinosaurs with his son Bastian and crafting the occasional work of fiction.