Huge but harmless spider species, a relative of garden spiders, is expected to spread up and down the East Coast

A female Jorō spider in Hoschton, Ga.
(Photo by Jeremy Howell)

A huge—but harmless—invasive spider species has spread across Georgia and other parts of the Southeast, and scientists say it will likely make its home up and down the East Coast, Jordan Mendoza reports for USA Today.

It's called a Jorō spider, an orb-weaver a little bigger than your palm. It looks a lot like a common garden spider, but can be distinguished by its flashy red butt. It's native to East Asia, but likely hitched a ride to the U.S. in a shipping container about a decade ago. Jorōs were first spotted in Georgia in 2013, and have expanded their territory rapidly since then, Mendoza reports.

The spiders will probably spread up and down the East Cost in the coming years, according to a newly published study in Physiological Entomology. University of Georgia scientists wanted to figure out the potential range of the Jorōs, so they compared the species to its close cousin, the golden silk spider, Mendoza reports. Golden silk spiders—also called banana spiders—spread throughout the Southeastern U.S. over 100 years ago but have spread no further because they can't tolerate cold weather.

"The scientists collected the two species and measured numerous physical traits as well as how they adapted to different environmental conditions, including brief periods of temperatures below freezing," Mendoza reports. "The results showed Jorō spiders, compared to their relative, had a metabolism twice as high, a 77% higher heart rate in low temperatures and they survived 74% of the time in the temperatures below freezing, while the golden silk spider survival rate was only 50%. Scientists also noticed the species does well in Japan, with some regions that have climates similar to the Northeast."

So you may see a Jorō spider in your yard in the next few years, but scientists say you shouldn't worry. They love to gobble up obnoxious pests like mosquitos and stink bugs. And, like other orb weavers, they're not aggressive, and their fangs can't penetrate human skin anyway, Mendoza reports.