A million named — millions more hidden

Taxonomists have formally described and named a little over 1 million insect species. That already makes insects more than half of all known living things — but it is widely treated as a down payment, not a final total. Vast tropical canopies, soils and freshwater habitats remain barely sampled.

In 1982 the entomologist Terry Erwin fogged rainforest trees and extrapolated a startling 30 million species. Decades of better statistics have since pulled that back: the current consensus, from Nigel Stork’s 2018 review, is around 5.5 million insect species — meaning roughly 80% are still undescribed. At about 20,000 new species named per year, finishing the job would take centuries.

What actually counts as an insect?

An insect has six legs, a body in three parts (head, thorax, abdomen), a pair of antennae, an external skeleton, and usually wings. That rules out a lot of things people lump in as “bugs”: spiders and scorpions are arachnids (eight legs, two body parts), centipedes and millipedes are myriapods, and woodlice and crabs are crustaceans. The game above asks you to sort creatures into exactly these groups.

Why so many — and why beetles win

Asked what his study of nature revealed about the Creator, the biologist J.B.S. Haldane reportedly answered: “an inordinate fondness for beetles.” Beetles are the single largest order, near 400,000 named species.

Insects have had about 400 million years to diversify, and a winning toolkit: small bodies that fit tiny niches, fast reproduction that speeds up adaptation, a tough exoskeleton, and — crucially — wings, the first ever to evolve, letting them spread, escape and reach new food everywhere on land and fresh water. Almost the only place they failed to conquer is the open ocean.

The numbers stop making sense

Beyond species, the raw headcount is staggering: an estimated 10 quintillion individual insects (a 1 followed by 19 zeros) are alive at any moment — about 1.4 billion per person. Ants alone were estimated in a 2022 study at roughly 20 quadrillion individuals, about 2.5 million ants per human, with a combined weight exceeding that of all wild birds and mammals put together — and equal to about a fifth of all humanity. (The older claim that ants weigh as much as all humans has since been revised down.)

Are insects disappearing?

Even as we keep discovering species, there is real concern about losing them. A widely cited German study found that flying-insect biomass fell around 75% across protected areas over 27 years, and reviews point to habitat loss, pesticides, climate change, invasive species and light pollution as drivers. The science is still maturing — monitoring is patchy, especially in the species-rich tropics — so the global trend is genuinely contested in its details even as the warning signs are taken seriously.

Frequently asked questions

Sources

• Stork, N. (2018), How Many Species of Insects… Are There on Earth?, Annual Review of Entomology — ~1M described, ~5.5M estimated, ~80% undescribed.
• Schultheiss et al. (2022), PNAS — ~20 quadrillion ants; biomass exceeds all wild birds and mammals, ~20% of human biomass.
• Smithsonian BugInfo — ~10 quintillion individual insects alive at any time.
• Hallmann et al. (2017) and later reviews — declines in flying-insect biomass and drivers.

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