Butterfly populations have declined dramatically in many regions. Whether butterflies can suffer is debated, but their welfare as potential sentient insects and their conservation both deserve attention.
Butterfly welfare exists at the intersection of conservation concern and uncertain sentience. Current evidence suggests butterflies have relatively simple nervous systems compared to vertebrates, but sublethal pesticide effects and habitat loss cause demonstrable impairment of behaviour. Whether this constitutes welfare harm in the morally relevant sense is uncertain. Regardless, butterfly population declines signal broader ecosystem health problems that affect the welfare of many other species with more established sentience.