We probably all are familiar with tiger moth caterpillars, those fuzzy, orange and black “woolybears” used by children to predict the severity of the coming winter. I was always carrying woolybears around. When disturbed, woolybears curl into a ball. It was fun to see how long it would take a woolybear, sitting on one’s immobile hand, to open and crawl up your arm.
Ranchman’s tiger moth (Platyprepia virginalis) caterpillars, like the woolybears of my childhood, are black with orange hairs at their anterior and posterior. The middle portion of the caterpillar has long white hairs. As a child in Western Pennsylvania, I never saw a woolybear with white hairs, since ranchman’s tiger moths are a western species.
These caterpillars feed on a variety of herbs and grasses. Yesterday when Leonard and I were walking between the North and South Elkins Barns in Ash Creek Wildlife Refuge (Modoc County CA), hundreds of ranchman’s tiger moth caterpillars were feeding on mustard plants.
Ranchman’s tiger moth caterpillars are present in the fall but are not fully developed. These fall caterpillars overwinter and complete their development in the spring, pupate, metamorphose into moths and then lay eggs which hatch into fall caterpillars to begin the life cycle again.
Adult ranchman’s tiger moths have black forewings with many pale white to off-yellow spots. The hindwings are orange with black bands or are mostly black with orange spots. The thorax has dorsal anterior patches of yellow or orange. The adult ranchman’s tiger moth pictures are from a previous post. (Ranchman’s Tiger Moth on 06-09-19.)
Lest one believe that all tiger moth caterpillars are black and orange woolybears, I must note that not all moths in the general “Tiger Moth” group fit that description. Some are white or green or brown and display different color patterns. However, all have a dense coat of hairs and commonly roll into a ball when disturbed.