Larvae of the red Scarlett lily beetle, it's covering itself in poop in attempt to protect itself. This looks like an (Asiatic?) Lily. Remove any beetles immediately and crush them. They will drop themselves and play dead,so put a cup or shovel under them to catch or you might loose them. Then squish them quickly to kill, most humane and eco friendly option. I have alot of lily 150+ so I check daily and remove them often. You find them reproducing at this time too. Check the bottom of leaves for orange eggs and remove, also the larvae ofcourse. The beetles are beautiful, but you leave any your lily will be completely destroyed! They are witty and will hide, so check under leaves and in crevices.