Why There's Actually So Many Insects?

How many insects are there on Earth? This science documentary counts every bug alive right now: ten quintillion soil arthropods, twenty quadrillion ants, and the facts behind why insect species outnumber every other animal combined. Under one square metre of northern forest soil, scientists have counted up to two hundred thousand animals. A hundred trillion insects are airborne over the United States on an ordinary summer afternoon. About a million insect species have been named, and six weeks ago, a team who DNA-barcoded 1.6 million insects in Costa Rica put the real total at fourteen to twenty million, then called that a lower bound. We trace the whole forty-four-year argument: Terry Erwin fogging one Panamanian tree in 1982 and pulling twelve hundred beetle species out of it; the wasp whose blind, wingless, mouthless male is shorter than a single-celled amoeba; how one apple tree carried to America in the 1800s set off a chain reaction of new species climbing the food web; and a bacterium that cuts a species in half without touching its genes. Then the honest catch. The most quoted number in entomology is not about insects at all, and the tidy explanations - flight and metamorphosis and flowering plants - collapse against the fossil record. What is left is colder. Insects never out-bred the world. They simply almost never go extinct. How many bugs are alive right now, and how many are actually insects? Why is one in four named animal species a beetle? And if seventeen million insect species exist while we describe six thousand a year, what happens to the ones that vanish before anyone names them? Drop a comment: what's the strangest insect you've ever found somewhere it had no business being? ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ SOURCES ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ HOW MANY ARE THERE ▸ Rosenberg, Y., Bar-On, Y. M., et al. (2023). "The global biomass and number of terrestrial arthropods." Science Advances, 9(5): eabq4049. ▸ Schultheiss, P., et al. (2022). "The abundance, biomass, and distribution of ants on Earth." PNAS, 119(40): e2201550119. ▸ Tielens, E. K., et al. (2025). "Systematic continental scale monitoring by weather surveillance radar shows fewer insects above warming landscapes in the United States." Global Change Biology. ▸ Hu, G., et al. (2016). "Mass seasonal bioflows of high-flying insect migrants." Science, 354: 1584–1587. ▸ Smithsonian Institution (1996). "Numbers of Insects (Species and Individuals)." Information Sheet No. 18. HOW MANY SPECIES — THE ARGUMENT ▸ Erwin, T. L. (1982). "Tropical forests: their richness in Coleoptera and other arthropod species." The Coleopterists Bulletin, 36(1): 74–75. ▸ Haldane, J. B. S. (1949). What is Life? The Layman's View of Nature, p. 248. ▸ Li, X., & Wiens, J. J. (2023). "Estimating global biodiversity: the role of cryptic insect species." Systematic Biology, 72(2): 391–403. ▸ Li, X., et al. (2025). "The past and future of known biodiversity: rates, patterns, and projections of new species over time." Science Advances, 11(49). ▸ Colwell, R. K., Guzman, L. M., et al. (2026). "Constructing a lower-bound estimate of the global number of insect species on a hyperdiverse empirical foundation." PNAS, 123(27): e2524283123. BUILT SMALL — FLIGHT AND MINIATURIZATION ▸ Misof, B., et al. (2014). "Phylogenomics resolves the timing and pattern of insect evolution." Science, 346(6210): 763–767. ▸ Mockford, E. L. (1997). "A new species of Dicopomorpha (Hymenoptera: Mymaridae) with diminutive, apterous males." Annals of the Entomological Society of America, 90(2): 115–120. ▸ Polilov, A. A. (2012). "The smallest insects evolve anucleate neurons." Arthropod Structure & Development, 41(1): 29–34. WHY SO MANY SPECIES — AND THE HONEST CATCH ▸ Mitter, C., Farrell, B., & Wiegmann, B. (1988). "The phylogenetic study of adaptive zones: has phytophagy promoted insect diversification?" The American Naturalist, 132(1): 107–128. ▸ Ehrlich, P. R., & Raven, P. H. (1964). "Butterflies and plants: a study in coevolution." Evolution, 18(4): 586–608. ▸ Feder, J. L., Chilcote, C. A., & Bush, G. L. (1988). "Genetic differentiation between sympatric host races of the apple maggot fly Rhagoletis pomonella." Nature, 336: 61–64. ▸ Forbes, A. A., et al. (2009). "Sequential sympatric speciation across trophic levels." Science, 323(5915): 776–779. ▸ Zug, R., & Hammerstein, P. (2012). "Still a host of hosts for Wolbachia." PLOS ONE, 7(6): e38544. ▸ Condamine, F. L., Clapham, M. E., & Kergoat, G. J. (2016). "Global patterns of insect diversification: towards a reconciliation of fossil and molecular evidence." Scientific Reports, 6: 19208. ▸ Labandeira, C. C., & Sepkoski, J. J. (1993). "Insect diversity in the fossil record." Science, 261(5119): 310–315. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ For business inquiries: [email protected] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ #Insects #Bugs #ScienceDocumentary #Entomology #Evolution #InsectFacts #Biodiversity