During the larger mayfly hatches, such as the March browns and Brown Drakes, I like to use variant patterns for searching for larger trout eyeing the surface looking for larger morsels drifting by. Variants actually work well all summer long, especially during the evening hours on the northern Wisconsin freestone streams. Casting the fly upstream or across with an upstream mend to avoid drag and then giving the fly several slight twitches can entice a big trout to rise and devour the fly, even when nothing is hatching.
Variants are really just an overside hackle wing, a body and a tail. I generally try to use a hackle that is 1-1/2 times bigger than the normal hackle for the hook size. For example, for a size #14 hook I like to use hackle that is really for a size #10 dry fly. My favorite hooks for tying variants are either the Partridge Spider hooks (L3AS) or the Partridge barbless, SLD dry fly hooks.
The key to these patterns is finding rooster feathers with long, stiff barbs, which can be easier said than done. Since I like to use 3 feather tips for the wing I usually strip the barbs off the bottom of the feathers before securing the feathers to the hook shank. For the bodies I prefer to use stripped peacock quills or turkey biots, as well as fine dubbing at times. Although, I am not sure what you use for the bodies really matters since the bodies are so small and the flies ride so high in the water.
The tail fibers are Whiting Coq De Leon tailings. (I do not like to use the Whiting Coq De Leon rooster capes or saddles for tailings because I feel they are not stiff enough.) The best tailings I can find today come from the shoulder area of the roosters. Personally, I don't think the color of the tailing fibers really matters to the trout, just to the fly tyer.