Woolly Bear Caterpillar (Pyrrharctia isabella or Isia isabella) sometimes called woolly worm, is the caterpillar stage of the Isabella Tiger Moth. This moth is found throughout the United States and parts of Canada and Mexico. The fuzzy woolly bear caterpillars eat a wide variety of plants. They hatch from eggs during the warm weather months, and eat until they are mature. During the fall, seek out safe places to hibernate until spring. They will often hibernate under rocks, logs, cavities in bark, etc. They remain as caterpillars until spring when they spin their cocoons. About a week to two weeks later, the adult emerges to begin the life cycle all over again.