|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 .