The Deer Hair Bass Bug we teach in our class uses a strip of ultrasuede for its tail.
If you mean the little tie-up, Most of the Aztecs use the Tail Support Piece to help keep the tail from fouling in the hook. But on a few where that's not practical, like this Mouse, the Puff Tail method is used: within the first half inch of tail, tie a little knot of thread around the tail and give it a drop of cement, to create a bit of stiffness in the early part of the tail. The other main use is when adding an Aztec tail to cork poppers and such, where there's little room to be tying on materials, and where there may be hooks on rings dangling about. (A variation of it is also used to extend the length of an Aztec tail beyond the limit imposed by the nature of a staple yarn, but we won't go into that here.)
