- Lifespan
- 2–3 weeks as an adult moth
- Size & Weight
- Wingspan 32–42 mm; 0.4–0.6 g
- Habitat
- Open grasslands, rough ground, and coastal areas where ragwort plants are abundant.
- UK Distribution
- Widespread throughout England, Wales, and southern Scotland; more scattered in northern regions. Resident populations; additional summer migrants arrive from continental Europe.
- Diet
- Adults feed on nectar from various flowers including teasels, knapweed, and ragwort. Larvae feed exclusively on ragwort plants (Senecio species), accumulating toxic alkaloids for defence.
- Predators
- Birds (particularly warblers) are deterred by the moth's toxins, but some predators including spiders and parasitic wasps may attack larvae or pupae.
- Mating Season
- May to August, with peak activity in June and July
- Breeding
- Females lay eggs singly or in small clusters on ragwort plants. Larvae develop through 5 instars over 4–6 weeks. Single generation per year in the UK, occasionally a partial second generation in warm years.
- Behaviour
- Highly distinctive day-flying moth with bold warning coloration (red hindwings with black spots). Adults are active in sunny weather and often seen visiting flowers in daylight. The striking appearance advertises toxicity gained from ragwort consumption during the larval stage.