Here is a killer mysis shrimp pattern that I use locally. I know it is a bit larger than most mysis patterns, but it does the trick where mysis are present:
KG's South Fork Mysis
Hook:DaiRiki 125 size 16
Thread: 8/0 Clear Mono
Bead: 3/32 silver
Abdomen/Tail:Pearl Krystal Flash -
over-wrapped with clear mono tying thread
Thorax: Pearl Ice Dub
Tight Lines,
Kelly.
"There will be days when the fishing is better than one's most optimistic forecast, others when it is far worse. Either is a gain over just staying home."
Roderick Haig-Brown, "Fisherman's Spring"