During this fly tying tutorial, I tie the E/C Caddis (emergent / cripple) created by Ralph Cutter. This is a great pattern when fishing over pressured trout, especially in tailwater situations. On those waters, the cold temperatures can slow the emergence, making patterns like this one perfect imitations.
Here are some great resources to learn more about this pattern and to see the color change during a caddis emergence:
http://stevenojai.tripod.com/eccaddis.htm
https://www.youtube.com/watch?v=ZNHIdOYAhZc