Stonefly nymphs can be as big as the impressive Dinocras, which is an inch-anda-half long, or as small as the tiny needle flies, Lecuctra, which measure less than half an inch. One characteristic they share is a double wingcase that houses hind- and forewings of almost equal length. This striking trait makes it simple to separate stoneflies from other nymphs – try to make it obvious when tying artificial flies. I always include a double-barrelled wingcase on larger dressings, although I sometimes don’t bother on size 14 hooks or smaller. Other obvious features on the larger nymphs are the underparts, which are custard yellow. Where possible, I copy them because I think they add authenticity. Some fly-tyers will think this is an unnecessary embellishment, but picture a dislodged nymph being pulled along on tumbling currents towards a trout. It must flash dark-light-dark-light while struggling to gain a foothold. Rubber limbs are often used to add movement on larger, more outlandish patterns. On smaller dressings, I use CDC for the tail filaments and legs. Larger stones and boulders, especially those carpeted with moss are considered penthouse accommodation by the nymphs and are less likely to shift in a thundering spate, providing the nymphs with safety. However, enough insects are washed out, or lose their foothold, to be served to the waiting trout and grayling. You won’t go far wrong with a brace of stonefly nymphs tethered to a 9 ft leader. They should be 18 in-24 in apart with the larger (heavier) pattern occupying the dropper and a smaller (lighter) fly on the point. If wading, short-line nymphing methods will allow you to precisely present your flies and takes will often be confident. Where deeper pools exist, an indicator will help to determine takes at long range, especially when casting upstream and allowing the nymphs to freefall as they drift back towards you.