Like many other brightly coloured moths, it is unpalatable; the larvae use members of the genus Senecio as food plants.

The larvae absorb toxic and bitter tasting alkaloid substances from the food plants, and assimilate them, becoming unpalatable themselves.

An exception is among different species of cuckoo which eat hairy and poisonous caterpillars including cinnabar moth larvae.

They can grow up to 30 mm (1.2 in), and are voracious eaters; large populations can strip entire patches of ragwort clean, a result of their low predation.

Often, very few survive to the pupal stage, mainly due to them completely consuming the food source before reaching maturity; this could be a possible explanation for their tendency to engage in seemingly random cannibalistic behaviour, as many will die from starvation.