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Joro spiders the size of human hands are spreading across the US

Reuters, Doris Wai
8 Jul, 2024

  • Though they look scary, the East Asian species is very shy and eats pesky insects like mosquitos and roaches

Joro spiders, originally from east Asia, were first found in the US state of Georgia in 2014 and could spread as far north as New York or New Jersey this summer, according to experts. Photo: EPA-EFE/ University of Georgia
Joro spiders, originally from east Asia, were first found in the US state of Georgia in 2014 and could spread as far north as New York or New Jersey this summer, according to experts. Photo: EPA-EFE/ University of Georgia
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Where are Joro spiders originally from?

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Why could it be good to leave Joro spiders alone and not get rid of them?

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Where are Joro spiders originally from?

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Joro spiders the size of a human hand are spreading across the United States.

The East Asian species is named after the mythical Japanese creature Jorogumo. It can turn into a beautiful woman and trap men with silk. They have blue-black and yellow stripes, long legs and sometimes a splash of red. Joros may look terrifying but are actually quite shy.

“They’re not dangerous [and they do not bite],” said Daniel Kronauer. He is an associate professor at The Rockefeller University in New York.

Researchers at the University of Georgia found that most spiders freeze for less than a minute when disturbed. However, Joros can shut down for more than an hour.

They were first seen in the US state of Georgia a decade ago. Female Joros can grow as large as 20cm across, and males 10cm. Male Joros are usually brown and do not have many special markings.

Joros are native to China, Japan and Korea and can survive in the Himalayan foothills. Kronauer said they probably came to the US through cargo ships. Since then, Joros have steadily spread throughout the Carolinas, Virginia and Maryland.

But fear not, Joros are unlikely to bite humans or pets. They prefer to eat pesky mosquitoes, roaches, wasps and other insects.

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Why could it be good to leave Joro spiders alone and not get rid of them?