Many of us grew up with the story claiming Wooly Bear caterpillars could predict the upcoming winter by the size of their black and red-brown sections. That’s a comforting bit of folklore, but I wouldn’t make any plans based on it. Although less well known, there are many other caterpillars in our area that bristle with impressive hair (properly known as setae), such as this Yellow Bear caterpillar. The Yellow Bear (Spilosoma virginica) is the larval form of the Virginia Tiger Moth, a nondescript white moth.
Caterpillars molt several times before they pupate and turn into a moth or butterfly. Each of these molts (or “instars”) in the Yellow Bear’s case, is a different color, from the pale yellow of the earliest through beige, red-brown or nearly black. The few individual long hairs extending high above the body of the Yellow Bear are a trait that all its instars share and is a help in identification. Another characteristic is their ability to run very quickly–something we don’t expect a caterpillar to do.
There are usually two generations of the Virginia Tiger Moth per season in our area. A Yellow Bear caterpillar seen in the fall is looking for a dark, safe spot to hibernate until spring when the warming sun makes it safe to continue on its metamorphic journey.