Many fireflies use light signals to communicate with their mates. The color of their emitted light ranges from green to orange. Fireflies active at twilight tend to have yellow or orange signals, whereas nocturnal fireflies maintain the ancestral green light color. Across species, there is a match between emitted light color and visual sensitivity. Screening pigments in firefly eyes have been implicated in tuning visual sensitivity, yet it remains unclear how light color has evolved to match the visual sensitivity across species. We investigate the hypothesis that pigments are present in firefly light organs and tune emitted light color. Indeed, the same types of screening pigments present in the eye are also in the light organ, and could contribute to shifting emitted light color. There some variation in the types of pigments present in species with different light color Photinus (yellow to orange) and Photuris (green), with higher diversity of pterin pigments and genes involved with pigment granule formation in Photinus light organs.