"Little Sepia Sedge"
Glossosoma
califica
casebuilding
caddis pupa
to reveal larval
form, place mouse over image
larva: 3 mm / pupa: 3 mm / adult 2.5
mm 
A well-distributed caddis found mostly in the west, particularly Pacific mountains. Need cold, oxygenated water. Live singly as larva. Pupa congregate with cases made of tiny pebbles that attach to stones; look like a colony of igloos. Hatch over entire summer, so are available to fish throughout.
Other casebuilding caddis: "Medium Cinnamon Sedge", "Giant Red Sedge" , "Great Western Caperer" , "American Grannom" , "Medium Speckled Sedge"