Cinnabar moth and caterpillar

The adult moth is beautiful, slate-black with two red spots and two rosy stripes on each fore-wing, and with black bordered hind-wings that are also rosy red. It is named after the red mineral Cinnabar, which was once used as an artists’ pigment.

From May to July you might see the moths in the Reserve or along the Canal around the grasses and ragwort, perhaps during a sunny day, though they mostly fly at night.

A female will lay a few hundred eggs on the underside of the lower leaves of ragwort, in groups of around 50; on hatching in July the larvae are yellow and cluster for protection, but, as they feed and move up the plant to the flowers, they accumulate the plant’s bitter alkaloids, which stops the birds eating them. (If the plant is stripped, younger larvae may starve, or be eaten by their siblings).

At the same time the caterpillars’ colour changes into the typical fancy, golden-orange and black hoops, and long hairs grow. In the late summer of August, the mature caterpillars drop to the ground, and then spin a cocoon ready to overwinter in the soil. Next spring the adult moths will emerge to begin the cycle again.
 
 
Links to further information and images
 
Buglife
Natural History Museum

Ragwort

Drone fly on ragwort

Ragwort thou humble flower with tattered leaves

I love to see thee come and litter gold...

Thy waste of shining blossoms richly shields

The sun tanned sward in splendid hues that burn

So bright and glaring that the very light

Of the rich sunshine doth to paleness turn

And seems but very shadows in thy sight.

John Clare 1831

As you step through the gate of the nature reserve or walk along the towpath from June to November, amongst the grasses you will see large, flat-topped clusters of golden-yellow, daisy-like flowers; these sit atop long stalks carrying raggedy leaves (hence the name). Each plant is a biennial, meaning that it will flower in the second year (perhaps producing over 2000 flowers over the season) and then usually die.

By Hilly Orchard bridge

In the UK it is in the top ten of plants which show the best benefit to wildlife feeding on nectar (the bugs in return help pollinate the flowers). Around 35 insects, including seven moths and seven beetles, just rely on ragwort for their food. Various butterflies, hoverflies, moths, and solitary bees and wasps love it too; for hundreds of them, like the cinnabar moth, ragwort nectar and pollen is a really important larval food. Then there are parasites for some of these insects, and birds eat the seeds, so you can appreciate the plant’s amazing value to nature.

Hoverfly

Soldier beetles

Speckled wood butterfly

If you look out for the cinnabar moth caterpillars, wearing black and golden-orange striped pyjamas, you will see what a voracious appetite they have, sometimes stripping all the leaves. This can encourage the plant to grow a new basal rosette, and then it will last for longer, behaving more like a perennial. Animals, horses included, avoid eating the growing plant as the leaves contain bitter-tasting, alkaloid toxins, but the cinnabar moth caterpillar has evolved a way of storing the toxin, even retaining it after pupation. Birds then know to avoid the warning bright colours of the caterpillar and the moth if they don’t want a yucky meal.

 
Links to further information and images 
 
Greg’s Wildlife - Ragwort
Ragwort Facts