Bead Head Midge

Walk along the shoreline of the Deschutes River and study the vegetation growing on the rocks in the splash zone.  There is a lot of it is yellowish, greenish, stringy stuff that looks like some kind of algae.  Fact is, much of what you think is plant life is actually midge eggs; zillions of billions of them. Some species of midges lay strings of eggs on anything that is wet at the edge of the water.  This includes not only shoreline rocks but boats, oar blades and the waders of wading fishermen.  These eggs hatch into midge larvae.  Midge larvae are very simple worm-like creatures. You can imagine how many there might be in square foot of river bed. In fact, in a square yard of river bottom there can be thousands. That is a lot of food for trout and other fish. 
The following is quoted from:
Hatch guide For Western Streams - "Midge larvae are found in all types of water, though those in stillwaters tend to be larger than those found in streams.  They live on, or burrow into, the substrate and feed on algae or decaying plant and animal mater, though a few species prey on smaller insects.  In streams the larvae are found in most water types, but bottoms where debris settles often have dense populations of midge larvae.  Because midges have several generations per year, larvae are present in streams all year and are constantly found drifting in the currents.  Even though they are small, the large numbers found in the "drift" offer trout a steady supply of food when other insects are not available.  In heavily fished streams, trout often feed selectively on midge larvae, even when other insects are hatching."
The flies below are effective midge larvae patterns for moving water, and still water.  Fish them dead drift along the bottom of any river, or suspend them under a strike indicator any time of year on nearly any lake. Fine tippets often increase strikes.