The cannabilistic Cinnabar

Tyria jacobaeae

This striking gold and black and surprisingly hairy caterpillar is the larval stage of the scarlet and dark charcoal Cinnabar Moth Tyria jacobaeae. The adult can be identified by the two bright red spots and the long red stripe down the leading edge of its dark grey/black forewing and its all red hindwing. It is named after the mineral ‘cinnabar’ once used by artists as a red pigment for painting. The bright colours of both the adult and larvae are a warning to predators that it is mildly poisonous.

The caterpillars feed on the yellow flowering Ragwort Senecio jacobaea which some of you may know can be poisonous to horses and cattle. The plant contains toxic and bitter tasting alkaloids which build up inside the caterpillars so any birds or predators that aren’t put off by the colouration will almost certainly be put off by the foul taste. Interestingly Cuckoos do not seem to be affected.

The caterpillars can become cannibalistic. This may be due to the fact that they are voracious eaters and often exhaust the host plant before reaching pupation. So, rather than face starvation they eat each other. Although grim as a survival tactic it makes sense.