Lightning bugs have a multi-year lifecycle that includes living in fallen leaf matter, hunting for other bugs, before emerging in like 2-3 years. So they need places that don't haul away all of the fallen leaves/plant matter or use broad spectrum pesticides.
I've always kept all the leaves in rows along our fences for the lightning bugs to live in, which is also popular with the song birds hunting for bugs. That and don't do the broad pesticide treatments.