Stoneflies
It rises on the Jurassic limestone near Essarois, runs through Montbard and Semur-en-Auxois, and gathers water from a long series of spring feeders as it goes. The character is limestone throughout: clear water, weedy pool tails, slow seams, and wild brown trout that know exactly what a size 16 olive looks like and what it does not. Fish the upper and middle reaches for brown trout and the occasional grayling. The hatches are strong — Baetis through spring, grannom in April, BWO throughout, and reliable caddis from May — and the limestone buffering keeps the river in condition even through dry spells. The trout are selective in the slow glides and bolder in the faster runs below the bridges. Start small — size 16 or 18 on fine tippet — and expect the fish to inspect rather than grab. The upper Armançon rewards the kind of patient, careful fishing that people associate with English chalk streams, without any of the associated expense or fuss.
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