Woolly worms turn into moths, not butterflies. The woolly worm is the larva of the Isabella tiger moth, a moth of medium size that has yellow-orange and cream-colored wings with black spots. It inhabits the entire United States as well as northern Mexico and the southern third of Canada.
The woolly worm, also known as the woolly bear or the banded woolly bear, is a reddish-brown caterpillar with black bands on each end. It has a fuzzy appearance due to a covering of short, stiff hairs. The woolly worm's body is composed of 13 segments. According to legend, narrower reddish-brown sections of the caterpillar mean that the following winter can be expected to be harsher.