Artificial light at night, or ALAN for short, may be one of the main drivers of firefly declines. At least 80% of the firefly species found in the United States and Canada communicate with each other using bioluminescent light signals in the form of flashes, flickers, or glows. These species are active at dusk or after dark, and artificial lights that are on at this time can make it harder for them to see each other. It may also make fireflies more vulnerable to predators that would otherwise be repelled by their light. The resulting decreases in reproduction and survival could have severe consequences for firefly populations.

This fact sheet is also available in Spanish: Conservando las joyas de la noche: Prácticas de alumbrado amigables con las luciérnagas