Why Did the Giant Leopard Moth Caterpillar Cross the Road?

Driving the back roads of Door County last weekend, you might have noticed the roads alive with woolly bear and related fuzzy caterpillars, such as this giant leopard moth caterpillar, on their annual fall migration, so many that no matter how diligently you might try to avoid them as you drive, you can almost hear the agonizing screams of the ones who don’t make it. What makes these little critters scurry across roadways as if their lives depended on it? They’re looking for places to winter such as old logs and leaf piles, where they hunker down for the winter. A sugar-based antifreeze known as a cryoprotectant keeps their cells from dying when their bodies freeze. In the spring they emerge, form a cocoon and turn into the beautiful giant leopard moth caterpillar. So the answer is, to get to the other side. Photo by Jim Lundstrom.