They’ve bugged off for sure.
Fossil records show that insects have been around for at least 400 million years, but it’s taken just three decades to wipe out more than a quarter of their global population.
The insect population shrunk by 27 percent since the early ’90s, according to a new report, which looked at data of more than 10,000 insect species across 1,676 locations. While analyzing 166 studies conducted between 1925 and 2018, scientists found that the average rate of decline per decade is 9 percent, though with notable variation between regions, according to the findings published Thursday in the journal Science.
“The decline across insect orders on land is jaw-dropping,” says Nick Haddad, Michigan State University butterfly expert, who was not involved in the report.
Haddad tells Associated Press that while the thought of fewer bugs may seem appealing, it’s bad news for the planet.
“Ongoing decline on land at this rate will be catastrophic for ecological systems and for humans,” he says. “Insects are pollinators, natural enemies of pests, decomposers and besides that, are critical to functioning of all Earth’s ecosystems.”
Other studies have previously revealed an average decline of 3 to 6 percent per year, such as in Europe and North America, particularly the American Midwest, who have lost an average of 4 percent of bugs per year.
Take California’s monarch butterfly: In the 1980s, the state enjoyed a monarch population of 4.5 million. Today, there are just 29,000. Meanwhile, a 2019 study found that 14 bee species from New England had lost 90 percent of their ranks since the turn of the 20th century. Bees and butterflies, of course, are vital pollinators, and play a critical role in the human food chain.
Conversely, freshwater insect species actually improved overall, by just over 1 percent per year.
Despite the good news for aquatic critters, Brett Seymoure, entomologist and postdoctoral fellow at the Living Earth Collaborative at St. Louis’ Washington University, calls the new meta-analysis more “overwhelming evidence” that insects are on the decline.
“It is likely that aquatic insect populations were in very rough shape and are now rebounding, which is great, but I don’t think we should take that as an indicator that the insect populations of aquatic habitats are as healthy as they were before the Industrial Revolution,” Seymoure tells Earther. “But it is a hopeful trend!”
Scientists suggest that human-induced climate change may be a factor, but, more specifically, industrialized farming and urban sprawl may be the key drivers of insect loss. They also point out that study data is lacking in some of the most biodiverse regions of the world, such as the tropics — the inclusion of which would likely impact overall results.
And the fact that our data only stretches back to the mid-’20s, long after the Industrial Revolution transformed human ecosystems, means our scope is limited. University of Delaware entomologist Doug Tallamy believes the decline may be even sharper than our relatively nascent data can reflect.
“We’ve been messing up ecosystems for an awfully long time,” Tallamy tells Earther.