Firefly populations are declining globally due to light pollution that disrupts their bioluminescent mating signals, habitat loss from development, and pesticide use. Over 2,000 species rely on species-specific flash patterns for mate recognition.
Fireflies unable to identify mates due to light pollution experience reproductive failure without finding alternative solutions — their mating system is entirely dependent on species-specific flash recognition. While the sentience of fireflies is uncertain, the disruption of fundamental life history processes at population scale represents a welfare concern alongside the conservation implications. Light pollution is a diffuse, widespread welfare harm that affects many night-active species simultaneously.