Cinnabar

Cinnabar Moth (Tyria jacobaeae)

Right now, our garden is heaving with Cinnabar Moths (Tyria jacobaeae). They flush from the grass pretty much everywhere we walk, fluttering low across the garden in an eye-catching flurry of matte black and red. We've just started finding some of their distinctively stripey offspring too; the black and yellow-orange caterpillars are currently devouring Common Ragwort (Jacobaea vulgaris) and Groundsel (Senecio vulgaris) plants scattered around the property. The species gets its name from its colour; not only are its forewings dotted and lined with red, its hindwings are solidly red as well. (Cinnabar is also the name given to the red mineral ore that we get mercury from.) The colour is aposematic; it warns potential predators that the moth (and its equally colourful caterpillars) are toxic, thanks to the alkaloids they ingest with their larval host plants. Only the Common Cuckoo can eat them without problems, and they've declined so drastically over the past decades that they're no longer a significant predator of caterpillars in the UK.

Native to Europe and western Asia, Cinnabar Moths are widespread across Britain. They have also been introduced to North America, Australia and New Zealand in an effort to control the Common Ragwort that was accidentally introduced there. Surprisingly, I recently learned that the Cinnabar Moth was named as a UK conservation priority species in 2007, which means it's considered to be among the country's most threatened organisms. That's certainly hard to believe from the numbers we see here!  Their vulnerability is due to the fact that their main larval host plant (Common Ragwort) is despised by livestock owners, as the ingestion of the plant can prove fatal to cows and horses. Many owners dig up every plant they find on their property. We have plenty of Common Ragwort plants in our garden (and some second-choice Common Groundsel as well), so our caterpillars should have lots of nosh — which is good, because in the case of a food shortage, they eat each other!

Caterpillar - Mike says they look like Oxford United scarves