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Joro spiders are here to stay - and spreading across the US

Joro spiders are tiny in the early summer, but by Halloween, they'll grow to as much as an inch wide.
Photo/Katie Tucker katietuckermedia@gmail.com
Joro spiders are tiny in the early summer, but by Halloween, they'll grow to as much as an inch wide.

Two years ago, ecologist Andy Davis found himself compelled to become a Joro spider expert.

“So, I’m not a spider biologist by trade, but because they’re in my backyard by the thousands, I simply had to become one,” he says.

Last month, Davis took me on a walk in the woods near the University of Georgia, looking for the spiders. They’re small in early summer – about the size of a pea or a grain of rice. That makes them hard to see, but Davis says they’re out here. And after some walking, we spot one, a miniscule spider in a tiny web.

In a few months, these tiny grains will be huge - over an inch or more - and they’ll be everywhere - just in time for Halloween

“They have a yellow coloring with these sort of greenish-blue bands across their back”, says Laura Ney, an extension agent in Athens. She works with farmers and gardeners on all things outdoors, including Joro spiders.

“And they have large legs with banding," she continues. "So they’re pretty striking – they’re actually, you know, an attractive spider.”

Joro spiders first appeared in Georgia nearly ten years ago, likely by hitching a ride on a shipping container from Southeast Asia. In 2019, when Joros started to pop up in large numbers in north Georgia, Ney got a lot of questions about them. What are they? And, are they dangerous?

Joro spiders are completely harmless to humans, but as to their effect as an invasive species? The Joro jury is still out.

“There’s no evidence that’s been reported so far that they’re having a detrimental effect, but of course in the grand ecological scheme of things, they’ve only been here for a really short period of time," Ney says.

But in that short time, ecologist Andy Davis has already discovered a few things. For example, they’re more comfortable than most spiders living among humans. They don’t seem to be bothered by us.

“I’ve seen them on gas station pumps, street lamps – I’ve even seen some on the top of street lights in the middle of a busy intersection downtown," Davis says. "I mean, that’s actually crazy to me, and so I’m fascinated by how they can do that.”

They also weave very durable webs, according to Davis.

“The Joro webs are so strong that a bird can actually land on them, stay there, and then fly off.”

Given how prolific Joro spiders are at reproducing, they’re likely to expand across the country. For one, they travel well, hitching rides on cars and trucks, Davis says.

“I know one was spotted in Baltimore. There’s been one in West Virginia. I talked to a student who was here at UGA who accidentally transported one to Oklahoma.”

So, Joro spiders may soon show up in a backyard near you, if they aren’t there already.

Martin Matheny is WUGA's Program Director and a host and producer of our local news program 'Athens News Matters.' He started at WUGA in 2012 as a part-time classical music host and still hosts WUGA's longest-running local program 'Night Music' which is heard on WUGA and GPB Classical. He lives in Normaltown with his wife, Shaye and dog, Murphy.