Insect and Spider Identification: Bioluminescent, possible larval firefly, 1 by mtnboondocks

mtnboondocks wrote:
I found these while walking the dog on the Cumberland Plateau in Tennessee. It's mid September and much to late in the year for the flying fireflies I know and love, but these guys are quite a green luminescent strictly under the very dorsal section of the abdomen. There were literally thousands that I could see as I walked, if I turned off the flashlight to see. All along the ground and over the gravel road. The dog seemed to be able to see or smell them as well, and it was a very foggy wet night following alot of rain. I spent a little time trying to google them, but they are much more "flat" in appearance than other pictures and have very bright luminescence on no more than 2 segments from what I could tell. Not the classic "glowworm" that I can find pictures of. Does anyone know the species? I mistakenly did not put any size marker in the image, but it's about an inch long when stretched out. Curls into circle (though not a "ball") when startled or touched.