Callibaetis spinner on an alpine lake in Washington's Cascades, the one referred to by the alias of Upper Lake in my Golden Trout trip report.
In this picture: Mayfly Genus Callibaetis (Speckled Spinners).
Troutnut.com is a collection of pictures and information about fly fishing. Fly fishermen, fly tiers, and trout enthusiasts of all stripes can learn more about life beneath the surface of trout streams, as well as how to better imitate aquatic insects with artificial flies to catch trout. There are aquatic insect pictures, underwater pictures, landscape pictures, and a comprehensive reference to the common names of trout stream insects.