The cinnabar is a moth of rough grassland and hedgerows, gardens and waste ground, where the black-and-yellow-banded caterpillars feed on common ragwort, other ragworts and groundsels. Adults are on the wing during the summer, flying in the sunshine, but also at night. They are easily disturbed, fluttering up from their feeding plants. The caterpillars pupate in autumn, spending the winter as cocoons on the ground, before emerging as moths the following summer. The bright colouring of the adults and caterpillars warns predators that they are unpalatable, having ingested the poisonous ragwort plants.