Stoneflies
Gammarids
It rises cold and clean out of the Jura plateau, runs for forty-odd kilometres through a steep limestone valley, and joins the Doubs at St-Hippolyte having done almost everything right. The trout are wild, the grayling are properly big, and the hatches are dense enough to make you grateful you brought reading glasses for your fly box. It was hit hard in the early 2000s by the same mix of agricultural runoff and mysterious fish-kill events that savaged the Loue, and the river still has its difficult days. But when it's on — a cool May morning with BWOs coming off a flat glide — it's as good as continental Europe gets, and you leave promising yourself you'll tell no one about it.
In chalk-spring and karst trout systems, generally stable temperatures broaden olive and other mayfly activity from early spring into autumn, with strong evening caddis, steady subsurface scuds and buzzers where clear groundwater and weedbeds develop, and terrestrials from meadow and woodland banks rounding out the food calendar, depending on how fast each river drops and clears after rain.
- Limestone