A new estimate of the total number of burrowing and buzzing ants on Earth reaches a whopping total of nearly 20 four billion individuals. That staggering number—20,000,000,000,000,000, or 20,000 trillion—reveals the astonishing ubiquity of ants, even as scientists grow concerned that a potential mass insect die-off could upend ecosystems. In a paper released Monday by the Proceedings of the National Academy of Sciences, a team of scientists from the University of Hong Kong analyzed 489 studies and concluded that the total mass of ants on Earth weighs about 12 megatons of dry carbon. In other words: If all the ants were taken off the ground and put on a scale, they would outnumber all the wild birds and mammals combined. For every person, there are about 2.5 million ants. “It’s unthinkable,” said Patrick Schultheiss, the study’s lead author, who is now a researcher at the University of Würzburg in Germany, in a Zoom interview. “We just can’t imagine 20 quadrillion ants in a heap, for example. It just doesn’t work.” Counting all of these insects — or at least enough of them to arrive at a correct estimate — involved combining data from “thousands of authors in many different countries” over a century, Schultheiss added. To count insects as plentiful as ants, there are two ways to go about it: Get down on the ground to sample leaf litter — or set tiny traps (often just a plastic cup) and wait for the ants to slide out. Researchers have been able to Their boots are dirty from research in almost every corner of the world, although some places in Africa and Asia lack data. “It’s a truly global effort that goes into these numbers,” Schultheiss said. Ants, like humans, have crossed almost every continent and every kind of habitat. Ground-dwelling ants are most abundant in tropical and subtropical regions, according to the research team, but can be found almost everywhere except in the coldest parts of the planet. Or as the famous author and antologist (that means ant scientist) EO Wilson once put it: “No matter where I go — except possibly Antarctica or the high Arctic, and I don’t go there because there are no ants there — no matter how no matter how different human culture is, no matter how different the natural environment is, there are ants.” The world, indeed, might be better off with all these ants. By tunneling, they aerate the soil and drag the seeds underground to germinate. They serve as a food source for countless arthropods, birds and mammals. While carpenter ants are a nuisance to homeowners, forests will be stacked to the brim with dead wood without the decaying power of wood-destroying insects. Entomologists are seeing alarming declines in insect populations beyond ants in Germany, Puerto Rico and elsewhere. Habitat destruction, pesticides, and climate change contribute to this potential-but-still-discussed “bugpocalypse.” More than 40 percent of insect species may disappear, according to a 2019 study, with butterflies and beetles facing the greatest threat. Scientists are not sure if the number of ants is also decreasing. “To be honest,” Schultheiss said, “we have no idea.” This is the next research question the team wants to answer. “We have not yet tried to show this temporal change in ant abundance,” said Sabine Nooten, an insect ecologist and co-leader of the study, from Zoom. “That would be something that would follow.” For decades, scientists have looked to laboratory ant farms to test theories about animal behavior. Ant scientist Wilson, who died last year, used his knowledge of ants to explain the genetic basis for cooperation between animals and highlight the sheer biodiversity of life worth preserving. In the 1990s, he made a rough estimate of Earth’s ant population with fellow biologist Bert Hölldobler. Their estimate was about 10 quadrillion — in the same order of magnitude as the latest and more stringent estimate published Monday. “In the case of EO Wilson, he was just a very smart man,” Schultheiss said. “He knew a lot about ants and basically had a gut feeling.” Sign up for the latest news on climate change, energy and the environment, delivered every Thursday
