Spiders eat more than 400 million tons of insects every year

A jumping spider is seen taking down a bush cricket -- one tiny fraction of the 400 to 800 million tons of prey researchers estimate spiders consume every year. Photo by David E. Hill/Peckham Society

March 18 (UPI) — Humans may believe they’re the ultimate carnivores — they do eat 400 million tons of meat and fish annually — but spiders are every much as voracious, if not more.

A team of European researchers estimate spiders consume between 400 and 800 million insects and other invertebrates every year. They detailed their estimate in the journal The Science of Nature.

Spiders are found in all types of habitats, including cities and deserts, but they’re most abundant in forests, grasslands and shrublands.

Using a survey of previous spider studies as a guiding dataset, researchers pegged the planet’s spider biomass total at 25 million metric tons. The scientists then tallied how much the average spider must eat to survive in each habitat type, or biome. They determined Earth’s spiders consumer 400 to 800 million tons of prey — including insects, springtails and other invertebrates.

Roughly 95 percent of the prey biomass is captured and eaten by spiders in forests, grasslands and shrublands, where habitats are rich in resources less often disturbed, allowing spiders to grow much larger than elsewhere.

“These estimates emphasize the important role that spider predation plays in semi-natural and natural habitats, as many economically important pests and disease vectors breed in those forest and grassland biomes,” lead study author Martin Nyffeler, a researcher at the University of Basel in Switzerland, said in a news release.

“We hope that these estimates and their significant magnitude raise public awareness and increase the level of appreciation for the important global role of spiders in terrestrial food webs.”