JUMP TO:
- What is a Joro spider?
- Are Joro spiders venomous?
- Do Joro spiders bite?
- What states are Joro spiders in?
- Where are Joro spiders coming from?
- What do Joro spiders look like?
- Joro spider size
- What to do if you come across a Joro spider
- Joro spiders are spreading in the U.S.
- These giant flying spiders have distinct markings.
- Experts explain if Joro spiders are poisonous.
Few things freak people out like spiders. And when they’re giant venomous flying ones, all bets are off. Joro spiders, which have four-inch legs and balloon through the sky, will potentially invade the New York area sometime this year, according to the New Jersey Pest Control. That’s understandably raising a lot of questions, including “are Joro spiders poisonous?”
Meet the experts: David Coyle, Ph.D., invasive species expert at the University of Clemson; José R. Ramírez-Garofalo, an ecologist at Rutgers University’s Lockwood Lab; Andy Davis, Ph.D., a research scientist in the Odum School of Ecology at the University of Georgia; Jim Fredericks, Ph.D., entomologist and senior vice president of public affairs at the National Pest Management Association (NPMA)
The arachnids originally invaded the U.S. from Japan, and they’re expected to stick around. But what is a Joro spider and how concerned about them should you be? Here’s the deal, according to bug experts.
What is a Joro spider?
Joro spiders are large, venomous spiders with four-inch long legs, says David Coyle, Ph.D., invasive species expert at the University of Clemson.
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“Joro spiders are a species of orb-weaving spiders—like what you might see in your garden during the summer—that are native to Asia,” says José R. Ramírez-Garofalo, an ecologist at Rutgers University’s Lockwood Lab. “Within the last 10 years, they were introduced into the southeastern United States, and have since established themselves.”
These spiders can fly, too. They use a technique called “ballooning,” where they release silk threads into the air that allow them to be carried by the wind. That said, you won’t see large Joro spiders flying around.
“The teeny ones that are young and the size of a poppy seed will let off some strands and get carried by the wind,” Coyle says. “But the big yellow ones we see are not flying. The laws of physics prevent that.”
Are Joro spiders venomous?
This is a little complicated. Joro spiders are venomous, meaning they make venom, Ramírez-Garofalo says. But all spiders are venomous, he points out. “Joro spiders are technically venomous, but their venom is not thought to be harmful to humans,” he says.
Andy Davis, Ph.D., a research scientist in the Odum School of Ecology at the University of Georgia, says he’s asked about this a lot. “The short answer is yes and no,” he says. “All spiders will bite you if you pick them up and handle them harshly. But if you leave them alone, they won’t bother you.”
Do Joro spiders bite?
Joro spiders can bite, but they’re unlikely to. “Joro spiders are really, really shy as far as spiders go,” Davis says, noting that he’s tested this in his lab. “Joro spiders are one of the shiest spiders ever documented,” he says. “Even though they look scary, they’re really docile.”
But bites can still happen, especially if you startle or scare a Joro spider. If you did happen to be bitten by a Joro spider, Davis says it would feel like a bee sting. “Your skin would have the same reaction as a bee sting, too,” he says.
Meaning, you should be just fine if a Joro spider bites you. “Unlike black widow and brown recluse spiders, Joro spiders are not considered a threat to human health,” says Jim Fredericks, Ph.D., entomologist and senior vice president of public affairs at the National Pest Management Association (NPMA).
What states are Joro spiders in?
Research published in 2023 found that Joro spiders have been detected in these states:
- Alabama
- Georgia
- Maryland
- North Carolina
- Oklahoma
- South Carolina
- Tennessee
- West Virginia
“They are definitely in Georgia, along with the Carolinas and Tennessee,” Doyle says. But the other states where Joro spiders have been spotted may only have a few of these spiders versus having an established population, he says.
Where are Joro spiders coming from?
Joro spiders are native to Japan, and it’s not entirely known how they got here. “They likely arrived in the U.S. by hitchhiking on vehicles and shipping containers from their native East Asia,” Ramírez-Garofalo says. They’re thought to have originally arrived around 2010, according to research.
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From there, they’ve ballooned or hitchhiked to other parts of the country. “They’re hitchhiking on cars—that’s how they’re getting to these more extensive states,” Davis says.
Joro spiders have established themselves in the U.S. and aren’t expected to leave. “There is no stopping their spread at this point,” Davis says. “There are millions of them. They will be here with us forever. We need to learn to live with them.”
What do Joro spiders look like?
Joro spiders have a distinct look that makes them easy to spot. These spiders have blue-gray and yellow coloring with red markings on the abdomen and black legs with yellow bands for females, Fredericks says. The males are “mostly brown,” he adds.
LITTLE DINOSAUR//GETTY IMAGES
The Joro spider has distinctive markings.
Joro spider size
Joro spiders can get pretty big. “The Joro spider is known for its large size compared to other U.S. spider species,” Fredericks says.
Female Joro spiders can be up to 4 inches, including the legs. But male Joro spiders are “much smaller,” with a body size of about 0.25 inches with “drab yellow and brown coloration,” Fredericks says.
What to do if you come across a Joro spider
Experts say it’s best to just leave Joro spiders alone if you can. “It’s not out to get you,” Coyle says.
A Joro spider is also unlikely to end up inside your home, Davis says. “They do not go into homes,” he says. “They’re fine living in a tree or bush or on your garage. At this point, there hasn’t been any documented evidence that they live in people’s houses.”
Instead, Joro spiders like to set up shop in bushes, porches, carports, and decks, Coyle says. If one is in your way, Coyle suggests removing it with a brush. “They also have very soft bodies—you can squish it,” he says.
Davis says that Joros have a seasonality: They’re tiny in the early summer, about the size of a grain of rice, and then grow to a more noticeable size in September and October. “They die off in the winter,” he says.
Overall, experts stress that there’s no reason to be scared of Joro spiders. “I’ve handled dozens of them already,” Coyle says. “They’re just out there, doing their spider thing.”
