This week I made an exciting find. While walking from my office to the house, I just happened to look down and spotted a woolly bear caterpillar curled up in the gravel. This was the first woolly bear I have seen this year.
The woolly bear is the caterpillar of the Isabella tiger moth (Pyrrharctia isabella). Stiff bristles cloak the caterpillar’s body giving it a fuzzy appearance. A rusty band extends across the midsection of the insect. Black bristles cover the front and rear portions of the insect.
When I spotted to fuzzy caterpillar, it brought back fond memories of my childhood. Back then, it was commonly believed the width of the rusty band can be used to predict the weather. According to popular folklore when the rusty band is wide, we are in for a mild winter. Conversely, when it is narrow we will have to suffer through a severe winter.
Entomologists tell us that the width of the rusty band is controlled by the age of the caterpillar and not the impending weather. As the caterpillar ages it goes through a series of molts. With each molt, the black bristles that comprise two black bands are progressively replaced with rusty bristles. Consequently, the width of the rusty band is broadest when the caterpillar molts for the last time.
From the looks of the caterpillar I found, if the woolly bear can actually predict the weather, the winter in my neck of the woods should not be too severe.
If you find a woolly bear crawling across your lawn or driveway, make a note of the width of its rusty band. Then next spring pull out the note and see if the woolly bear’s prediction was right or wrong.