This classic trout pattern was originally developed in the early 1900s. It is tied with palmered hackle of two contrasting colors. The main body is tied with a dark color (traditionally brown) for high visibility by the trout looking up, with a couple turns of a light color (traditionally white) for high visibility for the angler - particularly in low light conditions.
The Elk Hair Caddis is a staple in your trout fly box. Imitating a hatching caddis fly, it can be tied in sizes 10-20 and in just about any color combination of dubbing, hackle, and wing. They may be thought of for trout, but you can also find uses for them to target smallmouth bass and panfish.
The Green Weenie is a very popular fly that imitates an inchworm or caddis pupa. It can be tied in any color variation, but most commonly fluorescent green or chartreuse - just match the thread to the body! You can also tie this fly in varying weights. Leave the bead off to fish it on the surface or just below, or add some wraps of lead around the hook shank to fish it extra deep!