As far back as American colonial times, a popular belief in New England was Woolly Bear Caterpillars could forecast the severity of the upcoming winter. People would observe the width of the orange or brown band on their bodies to predict the severity of the upcoming winter. According to the folklore:
- Wide brown band: Indicated a mild winter.
- Narrow brown band: Suggested a harsh, snowy winter.
In 1948 Dr. C. H. Curran, curator of insects at the American Museum of Natural History, conducted an experiment to see if Woolly Bear Caterpillars could forecast winter weather. He collected as many Woolly Bear Caterpillars as he could in a day in Bear Mountain State Park, New York. He continued this experiment for the next eight years.
Dr. Curran observed that the number of segments of the brown band on the caterpillars was related to the severity of the upcoming winter. Over the next eight years, Curran found that wider brown band generally indicated milder winters, while narrower bands suggested harsher winters. Dr. Curran findings were not scientifically rigorous. He abandoned the study in 1955.
Dr. C. H. Curran’s Woolly Bear Study: *
| Year of Study (November) | Brown Band Segments (AVG) | Predicted Winter Severity | Actual Winter Severity |
|---|---|---|---|
| 1947 * | < 3 | Harsh | Harsh |
| 1948 | 5.3 (15 specimens) | Mild | Mild |
| 1949 | 5.4 | Mild | Mild |
| 1950 | 5.5 | Mild | Mild |
| 1951 | 4.2 | Harsh | Mild |
| 1952 | 4.2 | Harsh | Mild |
| 1953 | 5.4 | Mild | Mild |
| 1954 | 5.3-5.5 | Mild | Mild |
| 1955 | 5.2-5.3 | Mild | Mild |
* The Woolly Bear Study data above is based on a general understanding of Dr. Curran findings and the common interpretation of his research, derived from secondary sources and interpretations of his work.
In 1955 Dr. Curran said, he was stopping the experiment. For a while Woolly Bear Caterpillars had been accurate 3 years in a row, but “the little beasts have not proved reliable“
It’s fascinating how these old beliefs have persisted through generations. While the folklore about Woolly Bear Caterpillars predicting winter weather is charming, scientific evidence does not support this claim. The brown and black bands of Woolly Bear Caterpillars are influenced by factors such as their age, species, and how long they have been feeding, rather than being an indicator of upcoming winter conditions.
