Why Insects Can Never Be Giant Again?

When insects ruled the skies? This science documentary on prehistoric animals and insect evolution reveals how Meganeura, a dragonfly-like giant of the Carboniferous period, grew as big as a hawk, and what keeps every bug alive today so small. Wings wider than your shoulders. Jaws lined with teeth. A millipede-like Arthropleura as long as a car. For thirty years, textbooks said these extinct animals grew so big because the air held more oxygen. Then a scientist ran around his campus with a butterfly net, and a 2026 study in Nature found that nothing in the way insects breathe would stop a hawk-sized dragonfly from flying today. In this video, we follow the case from an 1880 fossil in a French coalfield to J. B. S. Haldane's 1926 prediction, the 1995 oxygen theory, beetles X-rayed in a particle accelerator, dragonflies raised in Carboniferous air, and 10,500 fossil wings that pointed to a very different culprit. We cover the largest insect ever found, insect-eating birds that devour 400-500 million tons of prey a year, insects that pump air like tiny lungs, the giant wētā of New Zealand, a stick insect that clung to a sea stack after rats took its island, and beetles shrinking as the planet warms. Could a griffinfly really fly through today's air? Why did insects shrink just as birds took to the sky? And if oxygen isn't holding them down, what is? Drop a comment: What's the biggest insect you've ever seen with your own eyes? ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ SOURCES ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ THE GIANTS ▸ Nel, A., et al. (2018). "Palaeozoic giant dragonflies were hawker predators." Scientific Reports, 8: 12141. ▸ Harvard Magazine (2007). "A Gigantic Dragonfly, and Its Modern Descendants." November–December 2007. ▸ Davies, N. S., et al. (2022). "The largest arthropod in Earth history: insights from newly discovered Arthropleura remains (Serpukhovian Stainmore Formation, Northumberland, England)." Journal of the Geological Society, 179(3): jgs2021-115. THE OXYGEN THEORY ▸ Haldane, J. B. S. (1926). "On Being the Right Size." Harper's Magazine, March 1926. ▸ Graham, J. B., Dudley, R., Aguilar, N. M., & Gans, C. (1995). "Implications of the late Palaeozoic oxygen pulse for physiology and evolution." Nature, 375: 117–120. ▸ Kaiser, A., et al. (2007). "Increase in tracheal investment with beetle size supports hypothesis of oxygen limitation on insect gigantism." PNAS, 104(32): 13198–13203. ▸ Geological Society of America (2010). "Raising giant insects to unravel ancient oxygen." News release, 29 October 2010. ▸ Westneat, M. W., et al. (2003). "Tracheal respiration in insects visualized with synchrotron X-ray imaging." Science, 299(5606): 558–560. ENTER THE BIRDS ▸ Clapham, M. E., & Karr, J. A. (2012). "Environmental and biotic controls on the evolutionary history of insect body size." PNAS, 109(27): 10927–10930. ▸ Dorrington, G. E. (2012). "On flying insect size and Phanerozoic atmospheric oxygen." PNAS, 109(50): E3393. ▸ Nyffeler, M., et al. (2018). "Insectivorous birds consume an estimated 400–500 million tons of prey annually." The Science of Nature, 105: 47. THE 2026 STUDY ▸ Snelling, E. P., et al. (2026). "Oxygen supply through the tracheolar–muscle system does not constrain insect gigantism." Nature, 653(8114): 439–443. ▸ Seymour, R. S., & Snelling, E. P. (2026). "Giant dragonfly extinction theory debunked." Australian Geographic (via The Conversation), March 2026. ▸ Howarth, T. (2026). "The (terrifying) reason these giant insects may not be gone forever." BBC Science Focus, 29 May 2026. THE LAST GIANTS — AND THE CAVEATS ▸ Priddel, D., et al. (2003). "Rediscovery of the 'extinct' Lord Howe Island stick-insect (Dryococelus australis (Montrouzier)) (Phasmatodea) and recommendations for its conservation." Biodiversity and Conservation, 12(7): 1391–1403. ▸ ABC News (2026). "New discovery of rare Lord Howe Island stick insect colonies." 15 March 2026. ▸ Te Papa Tongarewa. "Giant wētā (Deinacrida heteracantha) or wētāpunga." Collections Online. ▸ Tseng, M., et al. (2018). "Decreases in beetle body size linked to climate change and warming temperatures." Journal of Animal Ecology, 87(3): 647–659. ▸ Verberk, W. C. E. P., & Bilton, D. T. (2011). "Can oxygen set thermal limits in an insect and drive gigantism?" PLoS ONE, 6(7): e22610. ▸ Brand, U., et al. (2021). "Atmospheric oxygen of the Paleozoic." Earth-Science Reviews, 216: 103560. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ For business inquiries: [email protected] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ #GiantInsects #PrehistoricAnimals #Insects #Meganeura #Dragonfly #CarboniferousPeriod #Evolution #ExtinctAnimals #Paleontology #ScienceDocumentary