Phenology Friday, 4/3/2020

Woolly bear caterpillar 

By: Molly Olson, Naturalist/Program Coordinator

The woolly bear caterpillar is the larval form of the Isabella tiger moth. Many people know about the woolly bear caterpillar because of the legend that the woolly bear caterpillar can predict how mild or severe the coming winter will be. The wider the rusty brown band, the milder the coming winter will be. Dr. C.H. Curran, curator of insects at the American Museum of Natural History in New York City, started research to prove this legend in 1948. For 8 years, he studied the length of the brown segments and the forecast for the coming winter. In general, when the brown segment made up more than a third of the woolly bear caterpillar’s body, the corresponding winters were milder than average. His research, while limited, somewhat legitimized the folklore.

These caterpillars hatch in warm weather and search for places to overwinter, such as logs and leaf litter. In the spring, they spin cocoons and transform into full-grown moths. The woolly bear pictured below was found last week on RBNC trails.

1. Boeckmann, C. (2019, August 28). Woolly Bear Caterpillars and Weather Prediction. Retrieved from https://www.almanac.com/…/woolly-bear-caterpillars-and-weat…
2. Photograph 2: Isabella Tiger Moth. Photo by Andy Reago & Chrissy McClarren/Wikimedia Commons

@ River Bend Nature Center