A wide variety of caddis larvae and other insects have clustered together on the backside of this rock in fast water.
In this picture: Caddisfly Genus Neophylax (Autumn Mottled Sedges).
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.