Asset Warp problem.


I am trying to use the Asset Warp tool in Animate to animate a horse's tail. I find that the mesh extends well beyond the outline of the image. Can anyone show me how to keep the mesh within the image borders? The image of the tail was created in Photoshop, then converted into a movieclip symbol in Animate, then I converted the tail into a bitmap, so that I could use the asset warp tool on it. I am using iMac osx 10.14.2. Grateful for any help.