This is a wild valley only tempered by the hydroelectric dam at the top together with its feeder pipes, substation, lower dam and pylons. The fast-flowing stream runs down the steep valley through dense forest for some 10 miles to Château Verdun. At the furthest most point before the tarmac runs out there is a small car park with paths running up to mountain refuges and on into Andorra. Today there are just a couple of hardy fishermen trying their luck for a trout; as the afternoon turns to evening the clouds thicken and the rain that threatened arrives.

High in the wooded valley, and with the sun briefly out on the drive up, wood white, orange tip and clouded yellow butterflies are on the wing in sheltered clearings. Further up in the roadside scrub and sheltering from a passing rain shower is a clouded apollo; a local butterfly in the Pyrenees and a good find in the poor weather. My only other sighting was in similar roadside habitat on Lovćen Mountain in Montenegro back in May 2015. This is a species with a large population in Eastern Europe and isolated outposts in western and northern Europe; the foodplants are Corydalis species. In the Ariege, Corydalis solida is widespread in upland woodlands from March onwards.