Cinnabar Moth

The cinnabar moth is a member of the family Erebidae, in the tiger and lichen moth subfamily group known for bright warning coloration and chemical defenses derived from their larval host plants. It is native to Europe and temperate Asia and has also been introduced elsewhere as a biological control agent for ragwort.

Unlike most moths, the cinnabar is a day-flying species, and its striking crimson-and-black wing pattern functions as aposematic, or warning, coloration, signaling to potential predators that it is unpalatable. Both the adult moth and its caterpillar advertise this defense through bold, contrasting colors rather than camouflage.

The species is ecologically notable for its close relationship with ragwort and related plants, from which its larvae accumulate toxic pyrrolizidine alkaloids, making the caterpillars themselves distasteful to many predators and giving them a well-earned reputation as one of the most recognizable striped caterpillars in European meadows.

• Forewings sooty black with two red streaks and a red spot near the tip; hindwings mostly red with a narrow black border.
• Slender moth body, day-flying but also active at dusk, with a somewhat weak, fluttering flight.
• Caterpillar is boldly banded in alternating orange and black stripes running the length of the body, one of the most recognizable warning-colored caterpillars in its range.
• Distinguished from other red-and-black moths by the combination of mostly black forewings with red streaks and largely red hindwings; caterpillars are unmistakable when found in groups on ragwort.

Native to Europe and temperate Asia and introduced to parts of North America, Australia, and New Zealand, mainly to help manage ragwort. Found in open grassland, meadows, roadside verges, dunes, and waste ground wherever ragwort and related groundsel-type plants grow. Adults fly by day and at dusk during a single flight period in late spring and early summer.

Adults fly by day, relying on their bright warning coloration for protection rather than concealment, and feed little as adults, having built up reserves during the larval stage. Caterpillars feed gregariously in visible groups on ragwort and related plants, stripping leaves and flower heads, and accumulate defensive plant alkaloids from their host as they feed, a strategy reflected in their bold orange-and-black banding, which advertises this chemical defense to potential predators. Because of its close association with ragwort, the species has been used intentionally in some regions as a biological control agent for that plant.

Eggs are laid in clusters on the underside of ragwort leaves and hatch into small caterpillars that initially feed together in groups, becoming more solitary as they grow through several instars and develop their full orange-and-black banding. Mature larvae pupate in the soil or leaf litter, often after ragwort supplies are exhausted, sometimes forcing late-stage caterpillars to wander in search of a food source before pupating. The species overwinters as a pupa, with adults emerging the following late spring; there is generally one generation per year in cooler climates.