Most animals on earth are insects. In fact, 99% of the brains on earth may belong to invertebrates. And not all insects are pests — some are extremely beneficial to humans, and insects such as silkworms and bees have been domesticated for at least four millennia. With the recognition of environmental damage from animal agriculture, many are increasingly viewing insects as an alternative, sustainable protein source. In addition to pollination, farmed insects already provide pest control, recreation (for example, fishing bait), and animal feed. But if we choose to farm them on an even larger scale, we need to better understand their mental capacities. Can they feel pain? Are they self-aware? Indeed, given their brains, behavior, and communicative abilities, are they sentient? This review looks at evidence to answer these questions. 

Insects have been around for about 400 million years. Perhaps owing to this long history, their brains seem to be organized in a very efficient, functional way. Still, the number of neurons in insect brains is comparatively small. Bees, for instance, have 960,000 neurons, while a mouse has 75 million, and a human, 85 billion. Yet neuronal numbers may not be a reliable indicator of awareness or sentience. If an animal is aware of an external object or internal state, it is said to be conscious. Sentience requires that animal to be conscious of or responsive to sensory impressions. Insects display sophisticated behavior repertoires and cognitive capabilities out of proportion with their miniature brains. Thus, sentience may instead be more a function of brain organization, rather than size.

Animals, including humans, learn in different ways. In social learning, new behaviors come from observing and imitating others. In associative learning, an animal links an idea or behavior to an experience. Insects demonstrate both kinds of learning: crickets can learn how to hide from wolf spiders; bumblebees fly faster when there’s a sweeter reward involved; and jumping spiders display behavioral flexibility such that they will move away from prey before approaching, presumably to improve their odds of a successful hunt. 

Communication is another feature of higher cognition. Our ability to communicate verbally is often taken as evidence of our more advanced evolution. Since, as far as we know, insects don’t have language, they communicate in other ways. And yet, insects do vocalize; they also use touch, smell, sight, taste, chemicals, and vibration to exchange information.

One of the most vital issues when considering insect agriculture is whether insects can feel pain. Some recent evidence, while still not conclusive, suggests that this is the case. Science defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage.”  Nociception, on the other hand, is “the ability to detect stimuli that elicit damage to the body or the potential for such damage.” Thus, pain has an emotional component, while nociception is emotionally neutral. While insects display many behavioral or defensive responses to aversive stimuli, we don’t yet know for sure whether the insects feel “pain” — at least not in the way we think of it. 

Most people find insects disgusting. How we feel about insects will have a large impact on our view of them as separate from us, or as co-animals. It will also influence how we treat them, and the moral weight we give to their lives. As we consider this, it’s important to distinguish between animal welfare and animal rights. The concept of animal welfare grants animals a welfare interest, but greater human interests can override them. In that case, the animals must be treated humanely when their interests are breached. In contrast, when an animal has rights, its interests cannot be traded away for the benefit of others. 

If we decide to use insects as food, we will need to kill many millions of them — and realistically, if they become a true alternative, billions and trillions of them. However, the number may not differ much from the number killed for a plant-based diet. Here, the authors conclude that, given the current evidence, we can ethically farm insects for our benefit. However, we should use the precautionary principle and assume they can experience pain. The aphorism, “the absence of evidence does not equate to the evidence of absence” very much applies here. In addition, since insect species are enormously diverse, we may need to consider a species-specific approach. Brambell’s Five Freedoms may provide a starting place to create a humane production system for farmed insects. An international insect welfare charter could be another avenue to ensure the appropriate treatment of farmed insects.

While insect agriculture is not yet widespread, its time may be coming. The current horrors of factory farming for chickens, pigs, and cows crept upon us slowly. By the time we reacted, their suffering was, and continues to be, unimaginable. Advocates have an opportunity here. We can act now, while industry forces are still minimal, to protect the billions of insects that may eventually become part of the food system.