Joro spiders, an East Asian arachnid have been spreading throughout the southeastern United States.
Trichonephila clavata, also known as the Joro spider, is a member of the Trichonephila genus and is found throughout Japan, Korea, Taiwan, and China.
The Joro spider first appeared in the U.S. in 2013, when they were accidentally brought across from eastern Asia in a shipping container, according to a study published May 15 in the journal Arthropoda.
However, as of October 2022, T. clavata’s range spans at least 122 square kilometers (46,000 sq miles), occurring across Georgia, South Carolina, North Carolina, and Tennessee, with additional reports in Alabama, Maryland, Oklahoma, and West Virginia.
The yellow and blue-black critters are now found all over the southeastern U.S. where they weave exceptionally large webs measuring up to 6.5 feet in diameter (2 meters) that are sometimes interlinked to form “colonial” webs, according to Live Science.
The ‘gentle giants’ are very shy
“Most people think ‘invasive’ and ‘aggressive’ are synonymous,” study co-author Amitesh Anerao, an undergraduate biology major at the University of Georgia, said in a statement. “People were freaking out about the Jorō spiders at first.”
“If you’re an arachnophobe, they’re the stuff of your nightmares,” said Andy Davis, a biologist at the University of Georgia who studies them.
The species’ explosive spread suggested it could be innately combative and threatening. “One of the ways that people think this spider could be affecting other species is that it’s aggressive and out-competing all the other native spiders,” said Davis.
But Dr. Davis insists Juros are “gentle giants” that are prone to shyness and are more inclined to freeze than to fight. The results of his latest experiments show that the spiders remain stock-still for over an hour when puffed with air from a turkey baster.
By comparison, smaller spiders appeared relatively unfazed, indicating that even big, scary spiders can be scaredy-cats, reports the New York Times.
Joros have been the subject of media attention as they’ve spread; Dr. Davis suspects that they’ll reach New York this summer. Jorō spiders appear to be highly tolerant of human environments.
With how fast the spider has spread, Dr. Davis suggests that instead of being aggressive, the answer is their “incredible reproductive potential. They’re simply outbreeding everybody else. It’s not because they’re displacing native spiders or kicking them out of their own webs.”
People might hate the look of them, but Jorōs are relatively harmless and don’t bite unless they are cornered. The giant spiders are unlikely to budge from the southeast. “They’re so good at living with humans that they’re probably not going away anytime soon,” Anerao said.
Angela Chuang, a postdoctoral researcher at the University of Florida who was not involved with the study, notes that aggression, in terms of fighting with other creatures, is different from boldness or a lack of shyness.
“I would be very cautious about just calling them shy spiders — like, yeah, in what context?” Dr. Chuang said. “Apparently, it’s shy in the context of getting puffed with air, which tells us nothing about their actual interactions with any other species.”
If you spot a Joro, rather than running away or squishing it, Dr. Chuang proposed taking a picture and uploading it to a website like iNaturalist to aid researchers in tracking the arachnids. “Our research has been helped a lot by public awareness,” she said.
