Visitors exploring the Great Smoky Mountains may soon encounter an unusual sight: a large spider covered in striking yellow and black markings, with legs that can stretch several inches across.
The Joro spider has been gradually expanding its range in the United States, and officials at Great Smoky Mountains National Park are now asking visitors to help researchers track where the species is appearing.
But there is no need to panic.
Instead, park officials have a simple request: If you see one, take a photo and report where you found it.
A Spider That Is Hard to Miss
The Joro spider is an orb-weaving spider native to East Asia.
Adult females are particularly noticeable because of their bright yellow and black coloring. With their legs fully extended, they can reach roughly three inches, or about 8 centimeters, across.
That size can make them look intimidating, especially to someone encountering one unexpectedly along a hiking trail.
Great Smoky Mountains National Park officials have even joked that the spider looks like an “escapee from spider jail.”
But despite its unusual appearance, the main reason researchers are paying attention is not its size.
It’s where the spider is going.
The Joro Spider Has Been Expanding Across the U.S.
The species was first documented in the United States around 2013–2014, with researchers believing it likely arrived from East Asia through international shipping.
Since then, Joro spiders have gradually established themselves in parts of the southeastern United States.
Their ability to spread is particularly fascinating.
Young Joro spiders, known as spiderlings, can use strands of silk to catch the wind and become carried through the air. This behavior, sometimes called “ballooning,” allows them to travel surprisingly long distances without walking there themselves.
Over time, this can help populations expand into new areas.
Researchers have already documented the species across numerous states, and experts believe its range could continue moving northward.
Now, scientists want to understand exactly how far the spiders have spread through the Smokies.
Great Smoky Mountains Is Asking Visitors to Become Researchers
The park is not asking visitors to capture the spiders or interfere with them.
Instead, officials want people to observe, photograph and report them.
If you spot a Joro spider, park officials recommend taking a clear photograph and recording the exact location where you found it.
Reports can then be submitted through the free iNaturalist app or sent to researchers at the University of Tennessee.
Every observation can provide another piece of information about the spider’s distribution.
A photograph taken beside a trail, near a campsite or in another part of the park can help researchers build a more detailed picture of where populations are appearing.
Why Your Photo Can Actually Make a Difference
Scientists studying invasive species need large amounts of information to understand how populations move and establish themselves.
Researchers cannot be everywhere at once.
That’s where visitors can help.
A hiker who encounters a Joro spider may be standing in a location researchers have not yet documented. A single photograph, combined with its geographic location, can therefore become useful scientific data.
The more observations researchers receive, the easier it becomes to map the species’ expansion and identify patterns in where it is appearing.
Great Smoky Mountains National Park specifically said visitor reports will help University of Tennessee researchers map the spread of the species and better understand its expansion across the region.
When Are You Most Likely to See One?
Joro spiders hatch during the spring and become particularly noticeable during the warmer months.
They are generally most active through summer and fall, meaning visitors exploring the Smokies during these seasons have a greater chance of spotting them.
Their large webs can also make them easier to notice.
If you suddenly see a large, brightly colored spider suspended in a web near a trail, there is a chance you’ve encountered one.
The best response is simple:
Stop. Look. Take a photo. Record the location.
Then leave it alone.
Should You Be Worried?
For most visitors, encountering a Joro spider is more likely to be surprising than dangerous.
Their striking appearance can make them seem far more threatening than they actually are.
The important point for park visitors is that the species is being monitored because it is non-native and expanding its range—not because people should be frightened every time they see one.
That is also why officials are asking visitors not to disturb the spiders.
A photograph provides researchers with valuable information without unnecessarily interfering with the animal.
A Tiny Spider Can Travel Surprisingly Far
Perhaps the most fascinating part of the Joro spider story is how such a small creature can expand across enormous distances.
The spiders don’t need roads, vehicles or hiking trails.
Their young can use silk and wind currents to travel.
Once established in a new location, populations can gradually grow and spread again.
That combination of reproduction and wind-assisted movement has helped make the Joro spider an increasingly noticeable species in the southeastern United States.
And researchers are now watching closely to see where it goes next.
The Next Spider You See Could Help Scientists
The next time you’re hiking through the Great Smoky Mountains and notice an unusually large yellow-and-black spider, don’t immediately walk away.
Take a moment to observe it from a safe distance.
Take a photograph.
Remember exactly where you saw it.
Then report the observation through the appropriate research channel.
That tiny action could help scientists understand how an invasive species is moving through one of America’s most visited natural areas.
The Joro spider may have arrived in the United States accidentally more than a decade ago.
Today, researchers are trying to follow its journey.
And surprisingly, the next important data point might come from an ordinary hiker simply looking up at a spider web.