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Joro spiders are giant, colorful and a little creepy. Are they coming to CT?

FILE The Joro spider (Trichonephila clavata) making her web nests
Little Dinosaur
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FILE: The Joro spider (Trichonephila clavata) making her web nests.

Reports of the Joro spider entering the Northeast are making headlines as East Coasters become aware of the arachnid that can grow up to four inches.

While the spider currently lives mostly in the southern United States, its range has been expanding in recent years. Populations have taken up residence in Baltimore, and the spiders continue to move across parts of the South and East Coast.

Will their next destination be here in the Nutmeg state?

What is a Joro spider?

The Joro spider is a large, brightly colored invasive species native to East Asia.

They're part of a group of spiders called “orb weavers,” named for their wheel-shaped webs. The colors of the spider are striking — yellow-and-black-striped abdomens with pink or reddish markings on the stomach. Males are normally smaller than females, with blue-blackish coloring.

And their size is notable, too — the spiders can grow up to four inches when their legs are fully extended.

Their webs are often cast high in trees. “They are unusual for having very strong webs,” said Gale Ridge, an entomologist with the state of Connecticut. “Their webs actually have a golden color to them.”

Joro spiders are also often confused with the yellow garden spider that is native to Connecticut.

Where are they coming from? 

Joro spiders arrived in Georgia around 2013. Since then, their range has also expanded to parts of the Carolinas and southeastern Tennessee.

Similar to how the spiders first arrived in the U.S., if they quickly move up the coast, people are likely to blame.

“If they do make it up to the Northeast, it will be because they're attached to something that transports them,” said Gail Reynolds, master gardener coordinator at the University of Connecticut Extension. “It would take them years and years to get here [naturally] because they don't travel that far.”

Can Joro spiders fly? 

Not really. Call it “falling with style.”

Joro spiders don’t actually fly. “Like all spiders, they will distribute by sending out a small thread of silk, which catches the wind and then they fly off. It's called ballooning,” Ridge said. This is also how their offspring spread.

Is this species dangerous to the native insects in Connecticut? 

The Joro spider is an invasive species, but that doesn’t necessarily mean you’ll start seeing them taking over backyard gardens. The species is actually very shy and does not like to be bothered. They cast their webs very high in trees where agricultural pests may fly around.

“They are beneficial spiders and given the height, pretty nifty on mosquitoes and flies that tend to fly on a higher level off the ground,” Ridge said.

Are they dangerous to me or my pets? 

No. Their poison can only affect prey caught in their webs. A bite from a Joro spider cannot harm you or your household animals.

“Like if [a dog] went and put his snout through the web, it might land on him and feel threatened and bite him, but it would be the same as if a human did that,” Reynolds said.

Which parts of the state could they be in the most?

Believe it or not, they’re not climate-dependent, so the species would be able to live in temperatures along the coast or inland. “They’re found in Japan's high mountainous areas. They can tolerate extremely cold weather as well as semi-tropical weather, so the East Coast would be fine for them,” Ridge said.

Think you saw one? 

Snap a photo and send it off to an expert to be sure, Ridge said.

“My advice is that when people see it, get your phone, take a shot of it, and then email the photograph to my desk. And I can then answer yes, this is a spider of interest, let's take a look at it, keep it, don't kill it. Or don't worry, it's local, it's fine,” Ridge said.

The Associated Press contributed to this report.

Shanice Rhule is a recent graduate of the University of Connecticut where she has written for her school’s newspaper and radio station. She has previously worked with Connecticut Public as a Social Media Intern and is currently their Dow Jones Digital Media Intern for the summer of 2024.