CDC is one of those fly tying materials that has seemingly magical properties.  CDC is a fragile feather that imparts life like movement and flotation to fly patterns. Remember the admonitions to never add floatant materials to the CDC as this will destroy the natural buoyant properties. Hans Weilenmann writes at the Global Fly Fisher (GFF) about Tying With CDC. There is a great deal of information and links re CDC in the GFF post.

As I was studying up on CDC, I saw references to the Moustique style of fly pattern. This style of pattern uses a hackle collar of CDC at the front of the fly (as you would wrap a normal hackle in a dry fly or wet fly, you wrap the CDC feather). Normally, I have used a CDC plumes or puffs as a swept back underwing on wets and emergers. I have on occasion wrapped it once beneath an overwing of Elk Hair on Elk Hair Caddis to suggest legs.

The Moustique pattern is a simple pattern and the wing is one to two turns of CDC only. Check out the link at Rackelhanan re a simple Moustique Pattern