worm grunting
n.— «Earthworms are sensitive to low-frequency vibrations. These drive some types of earthworms to the surface, and in the southeastern US is used in a practice known as “worm grunting,” by scraping a piece of metal on a wooden stake in the ground. Within a minute or so, the vibrations bring the earthworms up to the surface where they are easily caught.» —“Weather Eye: look to earthworms for advice on flooding” by Paul Simons Times (London, England) Oct. 17, 2008. (source: Double-Tongued Dictionary)