Many people assume that insects don't feel pain, so often feel no remorse about hurting or killing them – but a study suggests this might be wrong.
Researchers from Britain and Iran reviewed previous studies on insects and pain, looking for similarities between humans and insects in their response to pain.
They focused on nociception – when the nervous system turns unpleasant stimuli such as fire and physical force into sensations such as pain.
The scientists found that insects seem to be able to 'shut down' pain using chemicals in their bodies, similar to how human beings can do when experiencing extreme pain.
Matilda Gibbons, of Queen Mary University, said: "One hallmark of human pain perception is that it can be modulated by nerve signals from the brain.
"Soldiers are sometimes oblivious to serious injuries in the battlefield since the body's own opiates suppress the nociceptive signal.
“We thus asked if the insect brain contains the nerve mechanisms that would make the experience of a pain-like perception plausible, rather than just basic nociception."
Insects are not protected by current animal welfare laws.
The scientists said their research shows that insects "most likely" have central nervous control of nociception, meaning they feel pain.
As discussions around insect farming become more frequent, the researchers argue that insects must be treated ethically.
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They write that insects “most likely have central nervous control of nociception (the detection of painful stimuli) and this consistent with the existence of pain experience."
They add: "We stand at an important crossroads of how to feed a human population projected to reach 10 billion by 2050, while conventional livestock farming is a major contributor to climate change. The United Nations recommends mass producing insects for food.
"However, ethical implications have not been thoroughly considered, since animal welfare protections tend not to cover insects.
"We argue that insects most likely have central nervous control over nociception, based on behavioural, molecular and anatomical neuroscience evidence. Such control is consistent with the existence of pain experience, with important implications for insect farming, conservation and their treatment in the laboratory."
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