CHICAGO — We'd have no chance against spiders.
Martin Nyffeler and Klaus Birkhofer's study published this month in the journal "The Science of Nature" notes that spiders eat between 400 million and 800 tons of prey in a year — more than the 7 billion humans on the planet and way more than the 2.7 million Chicago residents put down over 12 months.
The Washington Post pointed out that the total biomass of humans is about 360 million tons, a fraction of what spiders consume in a given year.
So spiders could realistically eat every human being quite easily in less than a year.
"I can't really check the math but I can believe it because spiders are everywhere," said Allen Lawrance, the invertebrate specialist at Peggy Notebaert Nature Museum. "What I find astounding though thinking about a sizable proportion that that 400-800 million tons of prey they consume must be pests like mosquitoes and houseflies. They really do provide valuable ecosystem services for us and we should be thankful that they are virtually everywhere, including in and around our homes."
Illinois is home to about 800 spider species, North America has about 3,000, and the world about 35,000. In Chicago, spiders will travel to the top of the city's tallest buildings, and they're probably in every single dwelling.
Only four species of spiders have venom strong enough to kill humans. In North America, the black widow spider is the only one.
