Rather than hijack a previous thread on the Galloup Butch Caddis, I thought I should start a new one.
Sorry, left out the "o" in Galloup........ Don't know how to edit the thread's name.
Kelly has a rather lengthy video on his origination of this pattern and gives very good reasons for its use. I will attach a youtube link to his video. But, should you not watch the video, he designed this caddis pattern to handle quite rough water and still float. In addition, he fishes it as an adult female laying eggs and therefore jerks it under occasionally to have it pop back up. Thus, the fly has to be like a cork.
To achieve this, he has an underwing of Zelon or similar material, followed by another underwing of deer hair tips, and, finally, a bullet head AND the hollow butt ends of the deer hair.
My example is not the best obviously, but gives the idea if you don't watch his video.
Although he does not always do so for his own use, all his commercial ties of the fly have short rubber legs fore and aft. I try to stay away from synthetics like rubber and foam myself.
I tied mine with a green butt to represent the female egg-layer.
Kelly's video:
https://www.youtube.com/watch?v=A0U_TauQbrU