All five families of luminescent beetle, Phengodidae, Rhagophthalidae, Elateridae, Sinopyrophoridae, and Lampyridae are categorized into the Lampyroid clade. It has been determined that the luciferases and luciferin protein expressed in the photocytes of all species of firefly is homologous with that expressed in beetle species within the families Phengodidae, Rhagophthalidae, and Elateridae. In fact, every bioluminescent beetle species studied has been shown to use very similar mechanisms for light production in the photocyte. The beetle genus, Sinopyrophoridae, has been shown to exhibit biolumiescence although the exact mechanism is not known. It is believed that it shares homology with other genera of beetles however.  The first time the entire genome of a bioluminescent beetle was determined was in 2017 with Pyrocoelia pectoralis, a species of firefly, and in 2018, three more species of bioluminescent beetle had their genomes sequenced. Biolumiescence in beetles has been shown to serve multiple purposes including the deterrence of predators and the attraction of mates.
The variation in coloring among different species of firefly has been determined to be due to differences in the amino acid sequences of the luciferases expressed in their photocytes. Two luciferace genes have been identified in the genomes of fireflies. They are luc1-type and luc2-type. There is evidence that suggests that Luc1-type evolved from a gene duplication of the gene that encodes for acyl-CoA synthetase. It is hypothesized that the luciferase of click beetles evolved separately from that in fireflies being the result of two gene duplications of the acyl-CoA synthetase gene suggesting analogy instead of homology between the groups. Additional genes have been found to be related to the storage of luciferin.