Saddle-Case Caddis
Common Names: Igloo caddis
Scientific Name: genus Glossosoma
These little guys build a dome-like case from pebbles and attach it to a large rock in a riffle or a run with moderate to fast current. They are so firmly attached and protected that cased larvae are rarely found drifting in the current.
However, a larva will outgrow its shelter and leave it to build a new one. This happens often enough that uncased larvae are regularly seen--and eaten--by trout. So a creamy larva pattern dead-drifted near the bottom is a reasonable tactic in waters that are rich in saddle-case caddis.
Pupation occurs in the same water that the larvae lived in. During a hatch, dead-drift a pupa pattern near the bottom using trout indicator or tight line tactics; present the fly in riffly water or just below riffles. An unweighted pupa pattern can also be drifted near the surface, or you can present a Soft Hackle with a wet-fly swing. Another good strategy is a dry fly with a pupa pattern as a dropper or trailer; the dry fly acts as an indicator and sometimes is taken by the trout.
After the hatch, errant and unlucky adults fall onto the water, and a dry fly is the right choice. Bankwater downwind or downstream from overhanging trees is a good place to cast your dry.
Females swim or crawl underwater to lay eggs. You can fish a dry at this time, or go subsurface with a Soft Hackle or Diving Caddis pattern.
How to Match a Saddle-case caddis
Hatches are matched from Westfly's database of "standard" fly patterns.
LARVA COLOR: Tan, cream, yellow with pink tinge
PUPA SIZE: 3-7 mm
PUPA COLOR: Body--Tan or green. Shroud--Tan or light green shroud
ADULT SIZE: 3-7 mm
ADULT COLOR: Wing--tan, brown, or gray wing. Body--Tan or olive-brown
OTHER CHARACTERISTICS: Larva lives under dome-shaped case made from small pepples. Body, wing, and shroud colors can vary, so it's always best to check a natural insect where you are fishing. Colors will darken when the insect is ready to lay eggs.