Orvis has a device to retrieve flies out of trees which I copied for my own use. Take a tube a couple of inches long, the tube should be large enough to slip over the tip of your flyrod. I used a body off a small felt tipped marker, plug the end of the tube with a secure plug, attach a large fish hook with the point removed to the tube. Attach a sturdy cord to the hook, I think what I used is called masonry cord and has a breaking strength of around 125 lbs. I would recommend around 12 ft. or more. I wind the cord around a 2 x 4 pieces of flexible foam about an inch thick. It's good to have it attached to something that will float so you can retrieve it when it falls in the water. They usually don't float.