Spence's photo illustrates my own experience using various substances for wadding, including tow, leaves, and hornet's nest. You get a bit of burning going, but the material tends to be blown apart from itself enough that the embers can't reach new material, and burns out- most often before the material- I hate to call what leaves the barrel a "wad"---- hits the ground.
Since I am in the habit of a long follow-thru, and watch my wads leave the muzzle, I find them easily on both the range, and in the field. On the rare occasion when an ember is still "smoking" on the ground, its even easier to find, and step on to put it out by depriving it of both oxygen, and cooling the material by pushing it against the ground( a great heat sink).
Rub your shoe or boot sole on top of the wad back and forth a few times, to make sure all the embers are out, then remove your foot, and visually check it for any living embers, and for smoke. I like to take my trash out of the field, so I also then pick up what I can and put it in my waste bag. :surrender: :thumbsup: