Are ‘giant, flying’ joro spiders really taking over the U.S.?

The black-and-yellow arachnids are making headlines again, but scientists say not to be alarmed.

A female joro spider tends her web in Oconee County, Georgia, in 2021.

PHOTOGRAPH BY DAVID COYLE, CLEMSON UNIVERSITY

ByJason Bittel

June 06, 2024

Joro spiders are in the news again, and judging by the headlines, everyone is doomed.

“Giant venomous flying spiders… heading to New York area,” says CBS News. “East Coast braces for invasion of palm-sized venomous spiders capable of flying,” echoes Fox Weather. And The Guardian calls the arachnids “gag-inducing.”

Of course, the scientists who study these animals, which are native to Asia, say such descriptions are misleading at best.

Floyd Shockley, an entomologist and collections manager at the Smithsonian National Museum of Natural History in Washington, D.C., says he’s “mortified” by some of the sensationalist headlines. “There’s no evidence that they’ve made it to New York.”

While it’s true that joro spiders arrived in Georgia in 2014 by unknown means and can survive in the United States, their colonization of the continent isn’t exactly imminent. So far, the spiders have been seen in Georgia, the Carolinas, Tennessee, and Oklahoma, with a few tiny satellite populations in places such as Maryland.

What’s more, threat posed by the black-and-yellow arachnids has been routinely exaggerated. (See beautiful photos of spiders.)

For instance, a recent Gothamist article describes the spiders as having “a body about four inches long and legs that span six to eight inches—about the size of a human hand.” 

“That is completely ridiculous,” says Shockley. “You’d have to stretch this thing out like a medieval torture device to get [its legs] even four inches, let alone six inches.”

What’s more, at this time of the year, every joro spider in the U.S. is no larger than a grain of rice. Adults die each winter, with eggs hatching in the spring and starting the cycle anew.

With so much misinformation afoot, let’s take a look at some of the other claims circulating online.

Can joro spiders fly?

“The way those headlines are written, it makes it sound like they’re the monkeys in the Wizard of Oz,” says David Coyle an assistant professor and invasive species expert at Clemson University.

In truth, none of the large adult joro often pictured in news stories are capable of flight. However, as spiderlings, joro and many other spiders can take to the skies in a common dispersal process called ballooning.

“Right after they hatch, the little hatchlings may be the size of a sesame seed,” says Coyle. “Some of them will get up high and they’ll raise their abdomen. They’ll put a few strands of silk out, and some of them will get carried away by the wind.” 

“I hate to tell people, but every spring, there’s probably thousands of little spiders ballooning over your head, and people have no idea it’s happening.”

As for their “flying” to new states, Shockley says “they have expanded their range, but it’s not surprising for an introduced species in 10 years to have moved, you know, a state.”