Here is the fly pattern sheet for the Mercury Cased Caddis.

Mercury Cased Caddis |
Mercury Cased Caddis Materials |




Dai Riki 060 or 730, #16 


Size 15 silver-lined glass bead


Black 8/0 Uni-thread

Rib (Optional):

Uni-wire, small copper or gold

Larva case:

Wapsi SLF Spiky Squirrel in brown or natural tan hare’s ear

Larva body:

Ice Dub Chartreuse

Larva head:

Black Hare’s Ear dubbing


  1. Place bead on hook and start the thread behind bead.
  2. Attach wire ribbing (optional).
  3. Dub a slender, tapered body; about two-thirds of the hook.
  4. Dub an Ice Dub collar.
  5. Dub a black fur collar and whip finish.

“One of the most prevalent caddis species in the Crooked River and other tail water fisheries in Central Oregon is the American Grannon or Mother’s Day Caddis (genus Brachycentrus). The caddis hatches by the thousands annually around Mother’s Day (early May) in most years. The caddis larva (bright green body with black head) is enclosed in a slender, dark brown case. If you’ve fished on the Crooked River, you’ve probably “caught” some of the empty cases. The caddis larva is a filter feeder that attaches to the upper surfaces of rocks in riffles and runs. Redbands and, especially, mountain whitefish eat all stages of the insect: larva, pupa and adult. This time of the year, a nymph pattern that imitates the cased larva will be a steady producer when dead drifted near the bottom in a rocky riffle or run. When I fish two nymphs, the nymph is positioned to be closest to the stream bottom. One of the best patterns that I have found to imitate the cased caddis is Pat Dorsey’s Mercury Cased Caddis. It is very effective and quick and easy to tie.” Bill Seitz

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