Many customers ask us about whether insects feel pain during their pest control treatments. Do flies feel pain? Do cockroaches feel pain? The science on the subject isn’t nearly as settled as you might think.
After all, pain as we know it is actually a complex neurological and emotional experience that can vary from person to person. Since pain is subjective on some level, scientists struggle with potential indicators of pain in animals. Behavioral changes may indicate something is amiss, such as when a dog becomes less social with its owners or when a cat stops eating. Discomfort in mice, rats, horses and rabbits can be evaluated on a “grimace scale” first developed to evaluate pain in children. When a rabbit is hurt, for example, you may see a stiffening of the whiskers, notice a narrowing of the eyes or observe it pinning back its ears.
To make matters more complicated, evolution discourages animals from displaying signs of weakness, since this makes them more vulnerable to attacks by predators. Since insects can’t make facial expressions to show us how they feel, are there any other ways to tell if bugs experience pain?
Do Flies Feel Pain? What About Other Insects?
Insect brains are far simpler than mammal brains. In many insects, these body parts are little more than dense nodes of neurons that process stimuli and control various parts of the body. However, insect brains still perform some of the same functions as their human counterparts. For instance, human brains have nociceptors that process and orchestrate the response to painful stimuli. While insects don’t have nociceptors, experiments have shown that they respond in the same manner as humans whose nociceptors have been activated.
In one experiment, fruit fly larvae which were poked with hot pins exhibited an immediate flight response. Scientists determined that this mechanism was due to a type of neuron that produced a response similar to nociception. However, it’s not clear whether this response can properly be called “pain”.
One entomologist points out that “mammals have a diverse response to pain, often avoiding use of the injured area and responding to different types of pain differently.” Experiments on fruit flies show a much different response: in some case, fruit flies rolled toward the thing that hurts them instead of away from it. The same experiment also showed that these insects have the same reaction, whether they are poked with a needle, a smoldering iron, blue light or hot water.
These studies give us no conclusive evidence to determine whether flies feel pain. What we do know is that insects can sense when they are in harm’s way and react to avoid risks that could cause damage. Although we can’t tell to what extent flies and other insects can sense prior injury or internal harm, their nervous systems are incapable of the emotional aspects of pain that we humans experience.
Do Cockroaches Feel Pain?
As we mentioned above, the scientific consensus holds that insects and other invertebrates don’t experience the same sort of consciousness that characterizes the human experience of discomfort. In other words, cockroaches and other insects can respond to stimuli, but can’t recognize patterns or “learn” from their experiences. These animals cannot experience grief or loss in the way that humans can.
Since insects don’t experience emotions in the same manner as humans, it’s difficult to argue that they feel pain as we do. After all, pain is a visceral, emotional experience that involves memory and other processes that don’t directly tie to stimulus response. By contrast, it’s more likely that insects—due to millennia of finely tuned genetic programming—perceive a harmful stimulus as something to be avoided. “Pain” may not enter into the equation.
An entomologist explores this issue even further in a graph which shows different responses to stimuli by different classes of animals. The graph shows that insects do not have protective behavior nor do they respond with high priority over other stimuli. The same entomologist points out that since insects are a large and diverse class of animals, they most likely interpret the world and “pain” in different ways.
Other Research on Pain
It seems that insects do not meet the standard definition of pain by the International Association for the Study of Pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.” Since insects don’t feel emotion, it would seem that they can’t experience pain, at least by this definition.
However, research is still ongoing on the subject. In a Forbes article, entomologist Matan Shelomi concludes that while insects can sense damage being done to them and can and will avoid it, they have a limited ability to sense past damage. He goes on further to say that not feeling pain is evolutionarily favorable for insects.
A fly has a short lifespan, with an average of 15 to 25 days, while the average lifespan of a cockroach is one year. Most insects have short lives, so if they worried about what could eat them, they wouldn’t be able to fulfill their primary purpose: mating and reproducing.
ABC Can Answer All Your Pest Questions
Despite the complexities of insect pain and consciousness, it’s clear that many homeowners prefer common household pests be removed in as humane a manner as possible. That’s why ABC utilizes a holistic integrated pest management approach to address unwanted insect houseguests. Our technicians can recommend changes to your environment to make your property less hospitable to these pests so that treatments can be low-impact. We listen carefully to our customers to design a pest control regimen that fits your family and addresses any concerns you might have.
