Cinnabar means to gild silver and gold to objects) "the toxic properties of mercury were well known. It was dangerous to those who mined and processed cinnabar, it caused shaking, loss of sense, and death. Data suggest that mercury was retorted from cinnabar and the workers were exposed to the toxic mercury fumes." Overexposure to mercury, mercurialism, was seen as an occupational disease to the ancient Romans: "Mining in the Spanish cinnabar mines of Almadén, southwest of Madrid, was regarded as being akin to a death sentence due to the shortened life expectancy of the miners, who were slaves or convicts."
Cinnabar moth moult (instars) they mainly feed on the leaves and flowers of the plant, and can be seen out in the open during the day. Like several other Arctiidae larvae, cinnabar caterpillars can turn cannibalistic. This is mainly due to lack of food, but they can eat other cinnabar larvae. Initially, the larvae are pale yellow, but later larval stages develop the jet black and orange/yellow striped colouring. They can grow up to , 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,