No one knows exactly how many species of insects exist. Taxonomists have estimated 8.7 million at one point, however, even that number was negatively criticized for being too small for Earth’s generous biodiversity. It has been said, over 10,000 new species of plants, fungi, bacteria, etc. are found each year. Insects too. 🙂

They outnumber humans in most geographical locations, especially as you move closer to the equator. I recall even seeing some flies in Iceland last year, which I thought was tremendously uninhabitable for any type of life besides humans who survive on fish.

Scientists have been continuously puzzled about whether members of the arthropod phylum experience pain, as mammals do. Scientists have concluded that insects lack nociceptors, which are the principal pain-receiving/experiencing components of the nervous systems of humans. However, B-endorphins and enkephlins have been detected in earthworms, suggesting the presence of a capacity for pain for annelids (Norman, 1900). However, many studies on nociception responses in insects are old and outdated. It is also quite challenging to design an experiment in which scientists can test the experience of pain within insects, rather than sole responses to stimuli.

Other research on another species of insects, predominantly within the arthropod phylum, have found that even when a limb is torn off of a cricket, they do not limp and their feeding and mating behaviors continue as normal (Eisemann et al. 1984). It could be very possible that limping from a limb injury became unnecessary for this organism with a 2.5 month lifespan. Since science has observed most animals carry out a purpose to procreate in their life, crickets may have evolved to not suffer from painful circumstances and carry out their purposes to the best of their abilities in their short, but meaningful lives.

With such a large spectrum of invertebrates, determining whether or not insects are sentient beings has been rather challenging to experiment.

Eisemann, C. H., Jorgensen, W. K., Merritt, D. J., Rice, M. J., Cribb, B. W., Webb, P. D., & Zalucki, M. P. (1984). Do insects feel pain?—A biological view. Cellular and Molecular Life Sciences, 40(2), 164-167.

Norman, W. W. (1900). Do the Reactions of the Lower Animals Against Injury Indicate Pain Sensations?. American Journal of Physiology–Legacy Content, 3(6), 271-284.