These caterpillars will turn into tiger moths. The coloration and the length of the bands do have a correlation to how severe the previous winter was. When they're born in the spring, they're all black, and the more warm growing season they have, the wider that round rust-colored band becomes in the middle. The coloring also indicates the age of the caterpillar. Each time it sheds its coat, it becomes redder. The furry coat protects them from freezing, down to -90 F.