It's that time of year when the woolly caterpillars are traveling. I'm not sure if they do it for several months, or I just remember that they cross the highways in September. As a naturalist, or a lover of nature, I veer a bit as I drive, trying to avoid smashing them.
Woolly caterpillars don't seem to be going in any one direction. Yesterday I saw two pass each other, one traveling east, and the other west. Folklore will tell you that if their all headed south, winter will be cold. Folklore will also tell you that the bands of black and brown can predict when winter will be cold or mild.
The common woolly caterpillar is the larvae of the tiger moth. In this case the term "common" is key, there are over 200 species of tiger moths. The scientific name for the one that so frequently crosses the road is Pyrrhactia isabella or the Isabella tiger moth. She, and I will always think of her as a she, was born from an egg in fall.
These seemingly misdirected wanderers are looking for a place to spend the winter, a dark and sheltered spot. The bristles act like insulation, slowing down the effects of freezing temperatures. Internally the caterpillar won't freeze, a chemical protects them, in fact they can survive -90 degrees Fahrenheit.
In their larval stage there are many food choices. Preferences are dandelions, sunflowers, nettles, and greens like cabbage, and spinach. The actual Isabella tiger moth will emerge from a cocoon in spring, living a few days and laying eggs for the generation before these October babies.
There are 13 segments or little ridges on their body, we also have thirteen weeks of winter (December 21 - March 20), hence the belief that they can predict our winter weather. Typically you have black bands at each end and brown in the middle. Black means cold, brown means less cold, or milder.
Some of the most profoundly intelligent gardeners will rely on the markings of the wooly caterpillar to predict winter. Of course there are other indicators; the thickness of an acorn shell and/or the height of a bees nest, which is best expressed with this old rhyme; "See how high the hornets’ nest, twill tell how high the snow will rest".
I decided a long time ago that I was a terrible predictor of winter. Those of us that have outdoor jobs are often relied upon for this kind of predictive power. Of course I observe the wooly caterpillars as they cross my path, and the bee's nests, and numerous other age old beliefs. But I don't count those wooly bands and mark my calendar, or crack open an acorn and measure its shell.
Knowingly or unknowingly, the wooly caterpillar has been right for a couple of years, or at least pretty darn close. Last winter came in very cold and fast, February say a big thaw, and March was rudely cold. So cold was last March and the March before that I have come to expect it.
Giving the weatherman some credit, the real prediction is for a milder winter with a weak El Nino. Today’s woolly caterpillar sported a thin black band for late December, a long brown band, and then a nasty looking black band to end it all. Seems pretty clear to me, but then I don't make these predictions.