Joro spiders spread east, on the move toward North Carolina

Large, yellow spiders not native to the United States have been spotted just south of North Carolina.

The joro spider is native to Korea, Taiwan and China. But in 2013 scientists found it living in Georgia.

Populations have been growing in parts of the South and East Coast for years, and many researchers think it's only a matter of time before they spread to much of the continental U.S.

But spider experts say we shouldn't be too worried about them.

"My sense is people like the weird and fantastic and potentially dangerous," said David Nelsen, a professor of biology at Southern Adventist University who has studied the growing range of Joro spiders. "This is one of those things that sort of checks all the boxes for public hysteria."

Scientists instead worry about the growing prevalence of invasive species that can do damage to our crops and trees - a problem made worse by global trade and climate change, which is making local environmental conditions more comfortable for pests that previously couldn't survive frigid winters.

Entomologists also worry the spiders could displace native North Carolina garden spiders like 'writing spiders' or 'banana spiders'.

"This is a new spider that is coming into new turf and it doesn't have complement or natural enemies that it has back in Asia," said Clyde Sorenson, NC State University. "So released from up that biological pressure they reproduce rapidly and they establish better. Since they are bigger they could be competing with our native spiders."

They're hard to spot at this time of year because they're still early in their life cycle, only about the size of a grain of rice. Adults are most commonly seen in August and September.

"They are going to build their webs above visitation where they can encounter flying insects," said Sorenson. "There is not much of habitat modification that you need to worry about. They are not a spider that prefers dark and dusty places like a black widow."

Still, despite being an arachnophobe's worst nightmare, there are zero reports of joro spider bites in humans in the United States.

Joro spiders have venom like all spiders, but they aren't deadly or even medically relevant to humans, Nelsen said. At worst, a Joro bite might itch or cause an allergic reaction. However, the shy creature tends to stay out of humans' way.

Experts say pesticides will work to kill individual joro spiders, but once one is killed, more are likely to move into the area.

WHERE ARE THEY HEADED?

Scientists are still trying to figure that out, said David Coyle, an assistant professor at Clemson University who worked with Nelsen on a study on the Joro's range, published last November. Their central population is primarily in Atlanta but expanding to the Carolinas and southeastern Tennessee. A satellite population has taken hold in Baltimore over the last two years, Coyle said.

As for when the species will become more prevalent in the Northeast, an eventual outcome suggested by their research? "Maybe this year, maybe a decade, we really don't know," he said. "They're probably not going to get that far in a single year. It's going to take a bunch of incremental steps."

CAN THEY FLY?

The babies can: using a tactic called "ballooning," young Joro spiders can use their webs to harness the winds and electromagnetic currents of the Earth to travel relatively long distances. But you won't see fully-grown Joro spiders taking flight.

WHAT DO THEY EAT?

Joro spiders will eat whatever lands in their web, which mainly ends up being insects. That could mean they'll compete with native spiders for food, but it might not all be bad - a Joro's daily catch could also feed native bird species, something Andy Davis, a research scientist at the University of Georgia, has personally documented.