The welfare of wild invertebrates including insects, spiders, and worms — often overlooked but potentially significant in aggregate.
Wild invertebrate welfare is the frontier of moral circle expansion — most people have not yet considered whether insect deaths from pesticide exposure, habitat loss, or light pollution represent welfare concerns. The scientific uncertainty about invertebrate sentience is genuine, but the precautionary principle applies: if there is meaningful probability of experience in these animals, and we are affecting them in the trillions annually through agricultural practices, the aggregate moral weight is potentially enormous even discounted for uncertainty. The interventions that would help wild invertebrates — reducing pesticide use, preserving and restoring habitat, reducing light pollution — have benefits that extend far beyond invertebrates and are worth pursuing on multiple grounds.