Cinnabar Moth
Tyria jacobaeae
Tap image to enlarge · Wikimedia Commons
Overview
The Cinnabar Moth is one of the most distinctive insects on the Sefton Coast. Adults are striking — black with crimson-red stripes and spots. But the caterpillars are even more obvious: jet black and bright orange in bold stripes, feeding openly on Ragwort in groups of 10, 20 or more. The warning colouring of both adult and caterpillar signals toxicity — they sequester the pyrrolizidine alkaloids from Ragwort. The bright orange and black caterpillars on Ragwort in August are one of the most striking sights on the dune grassland.
At a Glance
| Order | Lepidoptera |
| Family | Erebidae |
| Habitat | Open dune grassland · Rough grassland · Disturbed ground with Ragwort |
| Diet | Adults: minimal feeding. Larvae: Ragwort almost exclusively — the caterpillars sequester toxic alkaloids from the plant. |
| UK population | Widespread in England; numbers fluctuate with Ragwort availability |
| Sefton Coast | Common wherever Ragwort grows on dune grassland throughout the Sefton Coast |
| Conservation | UK Green List |
Where to See It
Wherever Ragwort grows on the dune grassland. Formby and Ainsdale.
Identification
Adult: black with red stripes on forewings, red hindwings. Caterpillar: bold black and orange hoops, feeding on Ragwort. Very distinctive at both stages.
Viewing & Photography Tips
Look for the caterpillars on Ragwort in August — they're conspicuous and easy to find. Multiple caterpillars on a single plant is typical. Adults are night-flying so usually found at rest in daytime.
Conservation Status
UK Green List
This species has a favourable conservation status in the UK and remains an important part of Sefton Coast biodiversity.
Frequently Asked Questions
Why are Cinnabar Moth caterpillars orange and black?
The bold orange and black pattern of Cinnabar caterpillars is aposematic (warning) colouration. By feeding on Ragwort, the caterpillars accumulate toxic pyrrolizidine alkaloids in their bodies. The bright colours advertise their toxicity to birds and other predators. Inexperienced birds may attempt to eat one but quickly learn to avoid the pattern.
Are Cinnabar Moths used for biological control of Ragwort?
Cinnabar Moth has been trialled as a biocontrol agent for Ragwort in New Zealand, Australia and North America where Ragwort is an invasive weed. In the UK context, both Cinnabar Moth and Ragwort are native species and part of the dune grassland ecosystem — high caterpillar numbers can defoliate Ragwort plants but rarely eliminate them, and the moths themselves are an important part of the food web.
Related Species
Plan your visit to the Sefton Coast
Marshside RSPB, Formby pinewoods, Ainsdale NNR — practical guides to getting there, what to bring, and the best spots for each season.