Do insects feel pain?
FACT CHECK: Whether or not insects can feel pain is subject to debate due to the fact that there’s no tangible way of measuring it. Here, we look at the scientific evidence...
This is Part 2 of a series of articles marking the release of our latest video - The Argument for Eating Insects (Instead of Going Vegan)
Humans are generally brought up to treat insects with both indifference and disdain. While kindness to a select few non-human animals (not including those we eat) is encouraged, insects are generally subject to active violence. Squashing them and trapping them without second thought is accepted, due to the fact that they are considered a nuisance, rather than beings with a right to live their lives.
Our treatment of insects is justified on the grounds that insects cannot feel emotions like us, and we are often told they are incapable of feeling pain.
But is what we understand about them correct? Are insects really incapable of feeling pain? We look at the science...
Do insects feel pain?
It is important to distinguish between ‘feeling pain’, which is a subjective experience, and ‘nociception’, which is defined as ‘the sensory mechanism that allows animals to sense and avoid potentially tissue-damaging stimuli’. Insects have been proven to experience the latter, but there is still no proof that this means they ‘feel pain’ in the sense that we do.
There is no direct way of measuring the subjective experience of pain in any being, including humans, meaning it can never be said for certain whether insects - or indeed any animal - are capable of it.
Professor Elwood, emeritus professor at the school of biological sciences at Queen’s University Belfast who previously studied pain in crustaceans, previously told the Guardian: “There is tremendous difficulty in asking questions about animal pain, because there’s no definitive experiment that will say: now I’ve proved it.
“That applies to all animals. We’re very accepting that cats and dogs experience pain – I think it would be the unusual person who said they didn’t, categorically – but it’s only done on probability. There’s no absolute proof.”
When it comes to other mammals, it is overwhelmingly felt that they feel pain because they have more similar nervous systems and responses to us than insects do. Our compassion comes more naturally for these animals, as we are better able to empathise with them due to the fact that they are closer to us in anatomy and appearance.
Invertebrates have a very different physiological make-up to mammals and humans, and some scientists have seen this as proof that they cannot feel pain.
A study titled ‘Is it pain if it does not hurt? On the unlikelihood of insect pain’ - published in The Canadian Entomologist in 2019 - concluded that it is unlikely that insects feel pain. They wrote that this was due to “our current understanding of insect behaviour, neurobiology, and evolution”.
The study said that the important difference between humans and insects in this context is the “lack of connections between relevant brain areas”, adding: “If the subjective experience of pain is produced by a network composed of brain regions that integrate sensory information processing, emotions, cognition, and memory, then it does not appear that insects have their relevant areas wired up in this way.”
However, a number of experts have highlighted that differences in insects’ make-up doesn’t necessarily entail a difference in pain capacity. Researchers have looked at how insects respond to injury, and come to the conclusion that there is evidence to suggest that they feel something akin to what humans class as pain.
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A 2019 study of fruit flies from the University of Sydney, published in the journal Science Advances, found that there’s evidence to suggest that insects have the capacity to feel persistent - or chronic - pain after an injury they sustained had healed.
Associate Professor Greg Neely, who led the study, said: "People don't really think of insects as feeling any kind of pain.
"But it's already been shown in lots of different invertebrate animals that they can sense and avoid dangerous stimuli that we perceive as painful. In non-humans, we call this sense 'nociception', the sense that detects potentially harmful stimuli like heat, cold, or physical injury, but for simplicity, we can refer to what insects experience as 'pain'."
"So we knew that insects could sense 'pain', but what we didn't know is that an injury could lead to long-lasting hypersensitivity to normally non-painful stimuli in a similar way to human patients' experiences."
One of the fruit flies in the study had one of the nerves in their legs damaged, which was then allowed to heal. After the healing process, researchers found that the fly’s other legs became hypersensitive. Professor Neely said: "After the animal is hurt once badly, they are hypersensitive and try to protect themselves for the rest of their lives.”
Clearly, this study seems to point to the conclusion that the insects’ pain went beyond ‘nociception’, due to the fact that the flies seemed to remember their injury and actively avoid it. This could well indicate that they had a negative experience of the pain they were subject to.
Read more: Do lobsters feel pain?
Does it matter if insects feel pain?
While there is no consensus on whether insects feel pain, it is arguable that this is irrelevant when it comes to their treatment by humans.
A being’s capacity to feel pain shouldn’t be a deciding factor on whether we willfully kill them or not, and we have no right to use it as a decider on who deserves to live.
We have such a limited understanding of insects and how they behave, interact, and live, but we know that many - such as bees, ants and wasps - are highly social creatures who live complex lives. All insects are so much more than the perceived nuisance they are to humans.
It is true, of course, that humans will inevitably kill numerous insects in their lives through no fault of their own - but that doesn’t mean we should take pleasure in swatting them just because they happen to annoy or disgust us. Because it’s so ingrained in us to find them irritating and gross, it is very difficult to feel empathy with insects in the same way as we do other mammals. But that is all down to perception, and doesn’t mean they are of any less worth.
If we can reasonably avoid killing any being, then surely that should be the correct moral decision to take. It is not up to us to decide which creatures are worthy of their lives.
WATCH: The Argument for Eating Insects (Instead of Going Vegan)
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Polly Foreman is a writer and digital journalist based in London. Since going vegan in 2014, Polly has stood firmly against all forms of animal oppression and exploitation. She is passionate about tackling misconceptions of veganism and challenging accepted norms about the way we use animals in this country.
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