|Wherever its larval foodplant, ragwort and groundsel, are present.
Newly hatched larvae feed from the underneath of ragwort leaves and
absorb toxic and bitter tasting alkaloid substances from the
foodplants, and assimilate them, becoming unpalatable themselves.The
bright colours of both the larvae and the moths act as warning signs,
so they are seldom eaten by predators.
20 mm long.
32 - 42 mm.
Up to 300 in batches of 30 to 60.
Cinnabar caterpillars can turn cannibalistic. This can be due to lack
of food, but they can eat other cinnabar larvae for no apparent reason.
This moth has proven to be particularly successful as a biocontrol
agent for ragwort when used in conjunction with the ragwort flea beetle
in the western United States.