Cinnabar moth caterpillars were feeding on ragwort. According to the Norfolk Wildlife Trust, the caterpillars feed on poisonous ragwort leaves, their body stores the alkaloid poison and passes this on through to chrysalis and finally to the moth. Predators such as birds that don’t heed their colourful warning soon learn how distasteful they are to eat!
The moths themselves tend to fly at night -- unlike the Burnet moth below, which flies during the day. Click on any picture to expand it.