Visitors in Great Smoky Mountains National Park are being asked to keep an eye out for Joro spiders, an invasive species known for spinning broad golden webs that can hang across trails at eye level. For Tennessee hikers, that means the next obstacle on the path may not just be fallen limbs or wildlife.
Officials say the request reflects the spider's continued spread across the Southeast and worries about both its effects on native habitat and how people experience the park.
What's happening?
According to Backpacker, Joro spiders are native to East Asia and have been expanding their range since they were first documented in Georgia in 2013. Park officials are now asking hikers to report any sightings.
The push follows the first confirmed sighting inside Great Smoky Mountains National Park in October 2024, when AmeriCorps volunteer Jarrett Rendon photographed one in the Cades Cove area, Backpacker reported.
Female Joro spiders are especially conspicuous: the black-and-yellow-striped spiders can measure about 4 inches across the legs, and their golden silk webs can spread as wide as 10 feet.
Though bites are uncommon and the spiders are harmless to people, their webs often appear near shelters, structures, and walking areas.
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As David Coyle of Clemson University, who studies forest health and invasive species, told Backpacker in 2024, "They do like to put their webs on places people go. Shelters, lean-tos. They're probably going to be there."
Why does it matter?
The bigger concern is not human safety, but ecological disruption.
The National Park Service said, as cited by Backpacker, that there is evidence that Joro spiders are displacing native orb-weavers in areas where they have become established.
Eye-level webs and unusually large spiders could discourage some people from hiking, camping, or using backcountry shelters.
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Researchers believe the species may continue moving north. A 2023 paper co-authored by Coyle found that the spiders are cold-hardy enough to potentially spread along much of the East Coast.
What can I do?
Park officials say visitor reports can help researchers better understand where the spiders are showing up.
If hikers encounter a Joro in Great Smoky Mountains National Park, they can record the sighting in iNaturalist, a widely used app for identifying and documenting plants and animals.
Still, experts caution that reporting sightings alone will not stop the spread. Coyle noted that Joro hatchlings can travel miles by "ballooning" on silk threads, which makes eradication especially difficult.
Even if local removal efforts reduce numbers in small areas, stopping the broader invasion is unlikely at this point.
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