Have you ever heard the tale that woolly “worms” predict the weather for the upcoming winter? Whether you believe it is fact or a tall tale, learn how to tell if our winter will be mild or cold by examining these interesting critters. Woolly “worms” are actually caterpillars and are the larval form of the Isabella tiger moth (Pyrrharctia isabella). The caterpillar’s body is made up of 13 segments that are either rusty brown or black in color.
Also commonly known as “woolly bears”, the caterpillars emerge from eggs during the warm summer months. When mature, they search for overwintering havens, such as under bark, rocks, or logs. This is why you see so many of them in the fall of the year.
Legend has it that the amount of black on the woolly caterpillar will predict how cold the upcoming winter will be. The blacker the caterpillar supposedly means that the winter will be colder, and the more segments that are black will determine how many weeks of cold weather the winter will have. The 13 segments represent the number of weeks in the winter; therefore, the more segments that are black will represent the number of cold winter weeks. On the other hand, the more brown segments there are, then the winter will be milder.
Do you ever wonder how folklore such as this gets started? In 1948, Dr. C.H. Curran, who was the curator of insects at the American Museum of Natural History in New York City, decided to do research on woolly caterpillars. He limited his studies to an area in the Bear Mountain State Park in New York. Dr. Curran collected samples and measured the length of the brown bands. He determined that if there were more brown segments versus black ones, then the winter would be mild. His findings were published in the New York Herald newspaper. As Dr. Curran’s research was confined to such a small area and for a short period of time, it was not conclusive scientific proof that the caterpillar’s coloration would predict how severe the winter weather would be.
There is some evidence that the woolly bear’s coloration is actually determined either by the maturity of the caterpillar or may have been determined by the previous winter’s weather. The earlier the caterpillar develops, then the more brown coloration it will have. Also, if it had a wide brown band, then the previous winter weather was mild.
Woolly Worm Festivals are celebrated in the fall all around the United States. If you find one of these fuzzy “woolly bears”, don’t depend on it to predict if South Carolina will have snow this year or not; but it’s fun to believe they do.