During their battle with the Night-Hookers, the spirits that died in the hands of their opponents became lightning bugs at the spot that they died and for that reason, their families wouldn't see them forever again, not even their dead bodies. Normally, what a spirit becomes after it's death depends on the community it stemmed from and to this particular community, lightning bugs is what they normally turn into immediately after their death. Most spirits' belief has it that the brighter a spirit shines after its death represents how long it has lived for but that was only a baseless theory.
Anyways, many spirits today in the battlefield had an unfortunate-unexpected death. It was unexpected because it has been so long since the last time in which the Night-Hookers attacked an escort of spirits like this one around this place. All they could theorise was that they were after that appearing person who was under the influence of a Sublime crystal.