Use a figure 8 wrap to compress the bunches and pull them on top of the hook shank. The figure 8 wrap is the trickiest part of the fly and will take some practice. This is the side view of the finished wrap.
To perform the figure 8 wrap start behind the wing. Start to take a wrap of thread, as your thread dips below the far wing (at about the 3/4 mark) you want to capture the base of the far wing with the thread by moving the thread in front of the wing, pinch the far wing with your off hand at this point and then cross the thread on top of the hook shank between the wings. You have just created the top portion of a figure 8. Apply enough pressure to bunch the wing fibers together and stand them up on top of the hook shank.