What we call woolly bear caterpillars are the larva of the Isabella tiger moth, or Pyrrharctia isabella. The tiger moth is a nocturnal flier with tan or light orange wings and a few black dots. This species thrives in gardens, pastures and fields across North America, extending into northern Canada and Alaska.

The first of two broods pupate in summer, with the second brood overwintering as a caterpillar that pupates in spring.

You probably don’t notice the caterpillars much in the spring and summer when they are feeding on their host plants, such as asters, clover, corn, birches, maples and sunflowers. You will start noticing them here in the Valley in a few weeks to “predict” winter, but mostly to fascinate kids and to remind us there isn’t much time until the snow flies.

The adults will feed in early spring for a few weeks, then spin a little oval cocoon out of their own silk and orange and black setae, emerging in another two weeks as fully formed adult moths.

After mating, the female lays her eggs on the vegetation. They hatch in a few weeks, and the cycle begins all over again. The species may go through two or three generations, depending on the region, before hibernating as caterpillars during the winter months.

Come fall, it’s time hibernate again. So, the woolly bear heads for some cozy place under a log or the bark of a tree, where it will sleep away the winter. By lowering their metabolism and creating their own form of natural antifreeze, they can be covered in solid ice and wake up just fine in the spring thaw.

Folklore of woolly bears predicting what type of winter we’ll have is one reason it’s so much fun to love these fuzzy creatures. If the woolly bears have a narrow, reddish-brown band, we’re in for a harsh winter. If these reddish-brown bands are wide, we’ll have a short, mild winter.

Other folklore talks about the black bands being the predictor — and that it depends on which end of the caterpillar is more black. But the variability of the bands depends on many factors.

As larvae mature, the reddish-brown bands lengthen. Wetter weather lengthens the black bands, so while not a reliable measure, it makes some sense that onset of an early and thus longer winter will force younger and less red caterpillars into hibernation.

I also love how they curl into bristly little balls when you pick them up. This defense mechanism earns them another common name — hedgehog caterpillar.

To see photos and detailed descriptions of these caterpillars, go to: http://go.osu.edu/woolybears.