Glowworms are rare in the northeast. The larvae are predators of millipedes and will suck the inside of the head’s contents out and then eat their internal organ, selectively leaving the millipedes’ defensive glands intact. The adults do not feed.
The adult females are larviform, meaning they look like the larvae. The attract a male with chemical signals and when close enough, the male then hones in on the light she is emitting. The luminscence in the larvae isn’t known. It’s been suggested that it has something to do with defensive signals. The larvae live in the leaf litter of a wooded area.
It is difficult to identify to the species level because they uniform in size, coloration, and shape, particularly those from the same general area. The distance between the eyes and the length of the antenna segments 4-6 are necessary to ascertain species.
Here’s a good overview from the U of FLA Entomology Dept