Cinnabar moth caterpillars

A cluster of cinnabar moth caterpillars are displayed in a glass jar. I found them feeding on ragwort plants on a hillside near our home in rural Douglas County, Ore., on Saturday, July 13, 2013. Cinnabar moths were introduced into North America to help control poisonous ragwort plants. The colorful caterpillars incorporate toxins from the ragwort and are unpalatable to predators. The caterpillars were returned to the plants after being photographed. 

The caterpillars can strip entire plants of leaves and flowers. They're also know to be cannibalistic.