Peek at any starter fly kit and theres likely to be some Montana Fly Company Elk Hair Caddis Flies included, and for good reason. One of the most effective dry flies of all time, the Elk Hair Caddis is hard to fish wrong, and is a solid choice when trout are feeding on a wide variety of insects, including stoneflies, mayflies, and caddis. The elk hair and hackle combine to let this pattern ride high, even in rough water. Per 12. Hook sizes: #18, #16, #14, #12. Colors: (009)Olive, (656)Tan. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Flies.