Discover nature this week with Missouri's caterpillars. While all bears are preparing for the winter, it's the familiar fuzzy caterpillar known as the woolly bear that clearly signals that cold weather is just around the corner.
On sunny autumn days, woolly bear caterpillars cross roads and highways. But even before there were paved roads, people noticed the woolly bear migration. They were the weather predictors of folklore.
However, their bristles function less for warmth and more for helping them to freeze over more controllably. The brown to black ratio is more an indicator of their age and how long they've been feeding than mild or harsh winter predictions.
As the days grow shorter and the nights grow cooler, most green plants stop growing. Woolly bears are leaf-eaters, and they are quick to notice the shortage of food. They, like many other moth caterpillars, can be parasitized by wasps that lay their eggs on them and eventually kill them.
Since caterpillars can't migrate south, their only option is to find a protected place to spend the winter. Hollow logs, piles of leaves, cracks in foundations and stacks of firewood are all good places to hide.
It is doubtful that the color of the woolly bear's coat reliably predicts the length of the winter, or that the depth of snow somehow correlates with the thickness of woolly bear fuzz, but their fall migration remains a reliable sign of impending weather. And if you didn’t know: The Woolly Bear Caterpillar eventually turns into the Isabella Tiger Moth (which there are about 60 species of).
Learn more about caterpillars in Missouri at MissouriConservation.org.
