The yellow bear caterpillar is the caterpillar of the Virginian tiger moth. The moth has a wingspan of about 2 inches and is white. The female lays eggs in groups on the surface of leaves, with each group containing a single layer of up to a hundred eggs. Young caterpillars tend to stay in groups and be lighter in color. The caterpillars disperse, feeding on a variety of aquatic and terrestrial plants, including maple and willow. With age, they grow up to 2 inches and may darken to a yellowish brown.

These caterpillars are covered with hairs (setae), but the yellow and black body can be seen below. The setae are used to form a cocoon when the larva pupates in order to winter over.

The more commonly known wooly bear caterpillar has shorter and stiffer setae.