What a Woolly Worm Knows

How to Read a Woolly Worm

September 18, 2019
Woolly Bear Caterpillar by SillyPuttyEnemies
SillyPuttyEnemies / Wikimedia Commons

It’s time again to shine the spotlight on a certain caterpillar—the woolly worm! According to folklore, this fuzzy fellow has the ability to predict the weather.

Also called the woolly bear caterpillar, the banded woolly bear, or just woolly worm, he’s the larva of the Isabella tiger moth (Pyrrharctia isabella).

In terms of appearance, the caterpillar has segments of either rusty brown or black. Often, he is black on both ends with rust-colored segments in the middle, although he might be almost all black or all rust.

Folklore says that if the rusty brown band is wide (more segments), then it will be a mild winter. The more black there is, the more severe the winter. 

Note that white, yellow, or other colors of fuzzy caterpillars are NOT the same type of woolly worm and are not used for weather forecasting. We’ll leave the weather-prognosticating “skills” to your own observation!

Learn More

For more woolly worm fun, check out the Woollybear Festival in Vermilion, Ohio! It’s the largest one-day festival in the state.

There’s also a Woolly Worm Festival in Banner Elk, North Carolina. Woolly worms race up to the top of their 3-foot-long strings, accompanied by thousands of cheers. The bands of the winner predict the coming winter.

Is there any real science behind the woolly worm’s predicting power? Read about the Legend of the Woolly Bear!

Watch a short video about the woolly worm:

To find a woolly bear, start looking under leaves and logs! Some are just crossing the road. Feel free to share your experience in comments below!

About This Blog

Your Old Farmer’s Almanac editors occasionally share our reflections, advice, and musings—and welcome your comments!