How do you define a proper caddis pattern? For us, its all in the profile. RIOs King Splitsville Caddis is a must-have in your   "buggiest" fly box. Thanks to those spilt wings, this caddis looks and behaves like an emerger, a fluttering or crippled adult, and a spent egglayer whether you dead drift it or skitter it. By combining an Elk Hair Caddis with a Hackle Stacker, Jonny King created one of the best caddis adults on the market.