An expert at Iowa State University’s Insect Zoo says there may actually be some science behind the folklore about how the thickness of a wooly bear caterpillar’s stripes can help predict the severity of the winter ahead. Ginny Mitchell, the insect zoo’s education program coordinator, says a fellow entomologist in New York studied the fuzzy creatures in the 1940s.
The black-and-brown caterpillars are prevalent in Iowa right now as they’re looking for safe places to spend the winter. As the story goes, Mitchell says the thickness of the caterpillar’s center stripe is key in weather forecasting.
There are also theories that if the caterpillar is crawling south when you find it, it’s trying to flee the looming northern cold, and the reverse, if it’s heading north, a mild winter is ahead. At least two communities — Vermilion, Ohio and Banner Elk, North Carolina — have fall festivals devoted to the alleged prognosticating abilities of the wooly bear caterpillar. One remarkable fact, Mitchell says these fuzzy critters hibernate during the wintertime and their bodies contain a sort of natural anti-freeze.
There are reports of wooly bear caterpillars surviving temperatures as low as 90-degrees below zero, even spending an entire winter frozen in an ice cube, to emerge just fine in the spring. Once temperatures warm up for the season, it will create a cocoon and emerge a few weeks later as an Alexandra or Isabella tiger moth.
