Firefly populations are declining globally due to light pollution, habitat loss, and pesticide use, raising both ecological and welfare questions about the scale of invertebrate population losses.
Whether fireflies experience anything resembling suffering is scientifically unresolved, but the question deserves consideration proportional to the scale of population decline. If insects have even minimal sentience, the loss of billions of individual fireflies represents potential welfare harm at a scale that dwarfs most other animal welfare concerns in raw numbers. The practical interventions available — reducing light pollution, avoiding pesticides in gardens, maintaining moist natural habitat — are low-cost and high-benefit under any reasonable assumption about insect welfare. They also benefit the vast network of other invertebrates sharing firefly habitat. The broader principle is that uncertainty about invertebrate sentience should motivate protective action rather than complacency, particularly when protective actions are low-cost relative to the potential welfare benefit if invertebrates do experience suffering.