"Small Spotted Sedge"
Hydropsyche
alternans
free-living caddis larva
To reveal the pupal form, place mouse over image
larva: 1/2" pupa:
1/2" 
adult 2.5 mm
These small, greyish-brown caddis are typical of this group and perhaps the best known. Prefer relatively fast water with stone/rubble bottoms. As net-spinners, they do not build a case, and are therefore available to fish as both larva and pupa. This species is found in the east, but close cousins are plentiful in the Rocky Mountain west. Adults are small, mottled yellow-grey, hatching in June into September. Unlike many caddis, they are active throughout the daylight hours, rather than being nocturnal, and therefore are more meaningful to fly fishers.
Other
free-living caddis:
"Little Orange Caddis" , "Dark Grey
Caddis" , "Western Olive
Sedge" , "Medium Dark Olive
Sedge"