Rare beauty of the washed-out mountain nymph

Avon Gorge: At first glance this moth might seem a simple, papery insect but its enchanting subtlety invites further study

Everything I've heard about the silky wave moth puts me in mind of fairy lingerie. It is small, pale tan, with a pearly sheen and delicate fringing at the edges of its wings. It appears from midsummer and is very rare, found in just one place in England and a further two in Wales.

Conservationist Jen Nightingale is taking me on a tour of the sites she surveys for the moths in the Avon Gorge. After two vertiginous rockfaces open to the growl of traffic on the Portway, I am relieved to be guided to something a little closer to a storybook scene.