Humans have been killing or injuring insects for millennia. Naturally, the question of whether or not insects feel pain might cross your mind. Well, the short answer is, “Not exactly.” Due to differences in the insect brain and body compared to higher-order animals, insects don’t feel sensations in the same way. Before discussing how that relates to painful stimuli, we must first understand how pain works for humans and other animals.
The IASP, or International Association for the Study of Pain, defines pain as an “unpleasant sensory and emotional experience” that usually occurs with some degree of tissue damage. Humans and many other animals have evolved the ability to feel pain as a way to protect the body from harm.
Many vertebrates, including humans, are able to feel pain because of the brain. When something hurts, the central nervous system operates by carrying signals from the pain receptors to the brain, and the limbic system triggers an emotional response to the pain. In humans, emotional responses to pain can include crying or an outburst of anger.
The brain also learns from the pain to prevent the pain-causing behavior from happening again. This is why most people who have touched a hot stove don’t plan on touching one again on purpose. Therefore, pain can be a powerful motivator behind animal behavior, as long as they have the capacity to feel it and learn from it.
The insect brain
Insects lack the same bodily systems that allow humans and other vertebrates to feel pain. Their nervous system is much simpler in comparison and lacks the ability to translate bodily stimuli into the emotional experience of pain. Also, insects don’t have the ability to store memory, which would allow them to “learn” from their pain. Instead, most of their behavior is simply instinctive, driven by a series of biological impulses.
Pain response in insects
Observing insects will also show you that there is little evidence they feel pain. Generally, insects don’t respond to pain-causing events the way humans and other animals do. Insects with lost limbs don’t seem to limp or writhe in pain. Also, insects with crushed abdomens will continue to crawl along if they still have their legs. Because insects have such short lifespans, there is no evolutionary advantage to being able to feel and learn from pain.