Scientists Want Your Help to Track the Spread of Invasive Joro Spiders at Great Smoky Mountains National Park
The invasive arachnids were first spotted in the park last year, and now, researchers hope to keep tabs on when and where they occur
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Planning a trip to Great Smoky Mountains National Park in the near future? Scientists want your help to track some large arachnids.
The National Park Service is asking visitors to be on the lookout for Joro spiders (Trichonephila clavata), an invasive species that was first introduced in Georgia and is now slowly making its way north.
The unusual-looking creatures have already reached Great Smoky Mountains National Park, which spans parts of Tennessee and North Carolina and regularly tops the list of the most popular national parks in the country. But researchers at the University of Tennessee want to get a better understanding of the spiders’ spread, so park officials are calling on citizen scientists for help.
“If you spot a Joro spider in the park, please upload a photo using the free iNaturalist app,” instructs an August 28 Facebook post from the national park. “Your observations will provide valuable data to help us better understand and manage this invasive species. Together, we can protect the Smokies’ natural balance.”
iNaturalist is a popular citizen science platform that allows users to upload photos and record their observations from nature. When thousands of individuals report specific plants and animals at different locations and times, trends and patterns often start to emerge. Scientists and conservationists can then use this trove of data to understand when and where organisms occur.
Joro spiders are native to East Asia. But somehow, the species hitched a ride to North America, showing up in Georgia more than a decade ago. Since then, the critters have been spreading across the Southeast and gradually heading north through the eastern states.
Need to know: Native species similar to the Joro spider
Garden spiders and golden silk orb-weavers can look similar to the Joro spider. Before the invasive species was introduced, golden silk orb-weavers were the only spiders from the Trichonephila genus in North America.
Adult females are large, measuring three to four inches across, including their legs. (For reference, that’s about the size of a human palm.) Males are much smaller, reaching about a quarter of a female’s size.
The spiders don’t technically fly, but juveniles disperse using a technique called “ballooning,” which involves releasing silk strands into the air, then using them to float around on the breeze. Joro spiders also build large, conspicuous webs that can span up to ten feet across and appear golden in sunlight.
“They do like to put their webs on places people go,” David Coyle, a forest health and invasive species expert at Clemson University, told Backpacker’s Adam Roy last year, when Joro spiders were first discovered in Great Smoky Mountains National Park. “Shelters, lean-tos. They’re probably going to be there.”
Despite their massive size, Joro spiders tend to steer clear of humans. In addition, their venom is weak, and their small fangs are generally not powerful enough to puncture human skin.
“They’re just not aggressive towards us,” says Karen Vail, an entomologist at the University of Tennessee, to WBIR’s Kaitlin Riordan. “The Joro might win the ‘shyest spider of the year’ award.”
In the park, the spiders have mostly been spotted in and around Cades Cove, a scenic valley surrounded by mountains on the Tennessee side of the protected area. Cades Cove is accessible to visitors via an 11-mile loop road, which provides access to hiking trails, a campground and a visitor center.
Joro spiders pose little threat to humans and pets. But, as with other invasive species, scientists are concerned about their impact on native animals.
“These large orb-weaving spiders are striking to see, but they pose a challenge: As they move into new areas, populations of native orb weavers have been shown to quickly decline due to competition,” according to the park’s post.
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