Insects are the most numerous animals on Earth, with estimates suggesting there are approximately 10 quintillion (10,000,000,000,000,000,000) individual insects alive at any given time. Trillions are killed annually in agriculture, pest control, and the growing insect farming industry. Whether insects can suffer is therefore one of the most morally consequential scientific questions of our time — and the answer is genuinely uncertain.
The sheer numbers involved make insect welfare a question of enormous potential moral significance. By some estimates, insect farming alone kills approximately one trillion insects per year, primarily for animal feed and, increasingly, for human food. Pesticide use kills vastly more. If insects can suffer — even in a minimal way, far less intensely than mammals — the scale of their suffering could dwarf that of all other animals combined.
This is why researchers at the Rethink Priorities think tank have invested substantial effort in assessing insect sentience. Their conclusion, published in a detailed 2021 report, was that the evidence for insect sentience is mixed and uncertain, but significant enough to warrant precautionary consideration. The question is not settled — but neither can it be dismissed.
The moral implication is not necessarily that we should stop all insect farming or pest control immediately. It is that we should take the question seriously enough to invest in research, develop more humane practices where feasible, and factor insect welfare into decisions about the growing insect agriculture industry.
Nociception: Insects clearly have nociceptors — specialized nerve endings that detect tissue damage — and respond behaviorally to noxious stimuli by withdrawing and avoiding the stimulus. This is a necessary but not sufficient condition for pain experience.
Opioid-like systems: Some insects, including fruit flies (Drosophila), have opioid-like systems that reduce responses to noxious stimuli. This is significant because the opioid system is specifically associated with pain modulation in mammals, not merely reflex responses.
Learned avoidance: Insects can learn to associate stimuli with negative outcomes and change their behavior accordingly. This suggests some form of memory of negative experience, though not necessarily conscious pain.
Motivational tradeoffs: Injured insects sometimes continue costly activities (like mating) at the expense of injury care, suggesting that competing drives and priorities influence their responses — a hallmark of centrally processed pain rather than simple reflex.
Stress responses: Many insects show physiological stress responses (elevated hormones, immune changes) to noxious stimuli that parallel stress responses in vertebrates.
Brain structure: Insect brains are radically different from vertebrate brains in structure. The specific brain regions associated with conscious pain experience in mammals — particularly the neocortex — have no clear insect equivalent. This does not rule out pain experience, but it means we cannot simply extrapolate from vertebrate research.
Behaviors inconsistent with pain: Insects sometimes continue normal activities (feeding, mating) after severe injuries that would be incapacitating for mammals. This suggests either that their pain experience is very different from ours, or that they have limited capacity for it.
Limited evidence for self-medication: Unlike some animals that seek out pain-relieving substances when injured, evidence for self-medication in insects is limited and ambiguous.
Uncertainty about consciousness: Even if insects process nociceptive information centrally, whether there is subjective experience — whether there is something it is like to be an injured insect — is deeply uncertain. This remains one of the fundamental unsolved problems in the science of consciousness.
The Rethink Priorities assessment concluded that the probability of insect sentience is meaningful but uncertain — perhaps in the range of 5-25% for some insects like bees, lower for simpler species. This uncertainty alone, combined with the enormous numbers involved, creates a strong case for taking the question seriously.
Of all insects, bees have perhaps the most evidence for morally relevant experience. Research by Lars Chittka at Queen Mary University of London has documented several striking findings: bees show evidence of pessimistic cognitive bias after negative experiences (a behavioral indicator of negative emotional states in mammals); bees seek out sugar solutions after stressful experiences in ways that parallel comfort-seeking in stressed mammals; and bees have been shown to engage in play-like behaviors — rolling small balls without any food reward — which is associated with positive emotional states in vertebrates.
Bees also have complex social lives, sophisticated communication (the famous waggle dance), and impressive learning abilities including face recognition. While none of this definitively proves conscious experience, it provides considerably more evidence for rich inner life than most insect species.
Approximately 100 billion bees are kept in managed colonies globally, with significant mortality from pesticide exposure, varroa mite infestations, and commercial beekeeping practices. If bees have meaningful welfare, the scale of potential concern is very large.
Insect farming is growing rapidly as a source of protein for animal feed and human food. It is often promoted as more sustainable than conventional animal agriculture — insects convert feed to protein more efficiently and produce less greenhouse gas than mammals or birds. From a sustainability perspective, the case is strong.
From a welfare perspective, the picture is more complex. Insect farms typically house insects at extremely high densities, control temperature and humidity to optimize growth, and kill insects through methods including heat, freezing, grinding, and CO2 exposure — all at industrial scale.
Research into more humane insect slaughter methods is nascent but emerging. Some evidence suggests rapid high-temperature killing may be less distressing than slow freezing for some species. The industry standard of grinding live insects is harder to evaluate given our uncertainty about insect experience.
The Insect Welfare Research Society and similar organizations are beginning to develop welfare standards for insect farming. Given the scale at which insect farming is projected to grow, establishing good welfare practices early in the industry could prevent enormous quantities of potential suffering.
Given the scientific uncertainty, what should individuals and policymakers do? Several principles apply:
Apply precaution proportional to uncertainty: When the probability of sentience is uncertain but non-negligible, and the numbers affected are enormous, even a small probability of experience justifies investing in research and developing better practices.
Support research: The most important action is investing in better understanding of insect neuroscience and consciousness. Organizations like Rethink Priorities and the Insect Welfare Research Society are doing important work in this space.
Influence the emerging insect farming industry: As insect farming scales, there is an opportunity to establish welfare standards while the industry is still forming. Consumer and investor pressure for welfare standards could have long-term benefits.
Be cautious about recommending insect-based foods as automatically more ethical: While insect farming is more sustainable than conventional animal farming, its ethical status depends on questions about insect welfare that are genuinely unresolved. Claiming insect food is automatically more animal-welfare-friendly than, say, sustainably produced chicken understates the uncertainty.