The rapidly growing black soldier fly and mealworm farming industries raise welfare questions about optimal rearing densities, as overcrowding affects larval behavior, cannibalism rates, and potential stress responses.
The welfare relevance of insect rearing density depends on unresolved questions about insect sentience. If larvae have any capacity for aversive states, then density-induced thermal stress and elevated cannibalism represent welfare costs that deserve minimization. The precautionary principle is particularly relevant here given the enormous scale of insect farming — billions of individuals — and the relatively modest cost of reducing density. Developing density welfare guidelines now, ahead of certainty about sentience, is prudent practice.