Letort Hopper. Bright yellow/greenish tint body in early summer, pale yellow body in mid summer and yellowish brown body in late summer/early fall. I fish them in size 10 and 12 with pretty good luck.

The other pattern I find productive in that area during hopper time is a yellow stimulator from size 10-16. I know it's not a hopper, but the trout don't seem to.