USA: Scary spiders up to 20cm in size are taking over the East Coast

Scary Joro spiders that grow to the size of a human hand are spreading across the East Coast of the US and heading north. But beyond their size and (manageable) poison, they are not aggressive, while they avoid humans. In the US, it didn’t take more than a few photos with the caption “Venomous Joro flying spiders are coming to New York” for citizens to panic and take cover to avoid being attacked by any “flying” spiders.

The Asian species is named after the mythical Japanese creature Jorogumo, which can transform into a beautiful woman and ensnare men with silk. With blue-black and yellow stripes, long legs and sometimes a touch of red, Joros may look intimidating, but they are actually quite shy.

“They are not dangerous. They are not aggressive. Even if you … hunted down the spider and harassed it enough to bite you, there wouldn’t be a problem,” said Daniel Kronauer, an associate professor at Rockefeller University.

Most spiders “freeze” for less than a minute when disturbed, but Joros can “freeze” for more than an hour, University of Georgia researchers found.

Don’t listen to the Joro spider slander! They are shy, build giant intricate webs and mind their business, I promise. pic.twitter.com/27R4gyhVON
— Gooood Milfical Morning☀️🍳 (@Lo_is_MEE) June 4, 2024

They first appeared in Atlanta, Georgia

Female Joros, first spotted in the United States in the state of Georgia a decade ago, can reach 20 centimeters in diameter and males 10 centimeters. The Joro, native to China, Japan and Korea and can survive as far as the foothills of the Himalayas, likely came to the U.S. via trade routes, Kronauer said.

“Most of these invasive species are spread by humans, often in cargo carried by ships as ballast.” Since then, they’ve steadily spread throughout the Carolinas, Virginia and Maryland, Kronauer said. “They are quite resistant to the cold. That’s why we can expect them to move further north.” The impact of Joros in the U.S. ecosystem is uncertain, although they tend to do very well in parks, gardens and parking lots, Kronauer noted.

“There’s a good chance that maybe this summer we’ll see some of that in New York.” But fear not, they are unlikely to bite people or pets. They much prefer to eat pesky mosquitoes, cockroaches, wasps and other insects. While they also help crops, like most spider species.

Don’t believe the buzz about Joro spiders! 🗞️ A recent #UGA study reveals these ‘gentle giants’ are harmless to humans and pets. Report sightings at https://t.co/OYlIgyCyBa. 📸 Carly Mirabile, University of Georgia, https://t.co/llX9a0PK8e pic.twitter.com/j9xpAsO819
— Center for Invasive Species and Ecosystem Health (@Bugwood) June 6, 2024

Do they have poison?

Experts say the Joro spider is not a danger to humans or pets. “They have venom just like any other spider,” says University of Georgia researcher Andy Davis. “But as long as you leave them alone, they’ll leave you alone.” Part of this has to do with the spider’s personality, which experts describe as quite docile and shy. Even if someone gets bitten by a Joro spider, expert David Coyle says it feels like a mosquito bite, while Davies compares it more to a bee sting.

Pets will also likely be safe around this species. Joro spiders spend the majority of their time in webs above ground, according to Davis, which are probably too high for a cat or dog to reach. Even then, any kind of attack from the spider should have been provoked.

“They’d rather not bite you because biologically, making venom for anything really costs a lot of energy,” says David Coyle. “They will only really bite if they are completely trapped as a last defense mechanism.”