Leave well alone!

These pretty yellow flowers belong to Jacobaea vulgaris,  a very common wild flower in the daisy family that is native to northern Eurasia. Its common names include ragwort, common ragwort, stinking willie, tansy ragwort, benweed, St. James-wort, stinking nanny/ninny/willy, staggerwort, dog standard, cankerwort and stammerwort. Ragwort contains copious alkaloids that make it poisonous to many animals.

Despite the presence of the poisonous alkaloids 6 spot burnet moths feed on the copious nectar of ragwort and the leaves are the food of choice for the caterpillars of the cinnabar moth. Such a diet means that  the moths and caterpillars themselves also become poisonous and their striking colouration is a warning to birds to leave them well alone. 

By good fortune  Ceridwen has today posted a splendid essay on such warning colouration.