The fully grown caterpillars can vary in colour from brown, grey to almost black.  The reddish dorsal line isn’t easy to see amongst the hair of fully grown caterpillars. The rosette like tufts of hair can be useful when identifying. These caterpillars are polyphagous, feeding on a wide range of herbaceous plants including dandelion, plantain, dock and heather. Overwintering caterpillars tend not to feed.