The Elk Wing Caddis dry fly is one of the most popular and proven dry flies in the world. The dry fly pattern imitates the natural caddis, one of the most prolific insects across North America that trout feed on. The elk hair caddis can be fished like any conventional dry flies, as well as be "skated" across the top of the water to attract feeding trout.
I would suggest having 3 of each color in your fly fishing case. That way you have multiple options when you are out on the water.