Above: #16 Fall Caddis Emerger with a Kapok dubbed thorax topped with a  mixture of Beaver Belly and Awesome Possum. Muskrats, otters, ducks, minks, beavers, and even polar bears have underfur that is waterproof and acts as a life jacket, keeping them very buoyant. Logic tells us that if we treat flies like Mother Nature treats her semi-aquatic furry friends, then we should engineer them the same way. Building up a buoyant underbody on my flies is something I often do, especially for thorax flies, as well as emergers and adult dry flies. You will not usually hear this conversation in the fly-tying world, primarily because everyone is caught up in silhouette, proportion, techniques, and so on. Let's discuss flotation. Creating underbodies built up with Kapok initially will better float your fly even after multiple hook-ups. I don't worry about the color of the Kapok because I'm covering it up with subsequent layers of dubbing. It's a simple step that will make your fly...