There are several Stonefly patterns around. I stick to the simple and classic design when fishing small creeks and calm waters. I will not try to take credit for this specific pattern, but I have adapted it to fit the waters where I fish. The variation of the pattern is called “Eltdalen”, and I tie it in three different colors. Eltdalen is the area where I start and end my fly fishing season.
This pattern is mainly used for spring fly fishing. It does not take very long for these bugs to start hatching after the snow has melted and the ice is gone from the water. But they do work throughout the season. The smallest variants in brown (and black) work well as midge imitations.
Please also see the yellow and green versions of this pattern on this website.