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Joro spiders, an invasive species from Japan, are here to stay
Spiders spotted in Braselton in 2014 are now spreading throughout Northeast Georgia
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A Joro spider hangs from its web on Oct. 11, 2019, in Gainesville. The spiders were introduced to Georgia from Japan, but the arachnids don't appear to be a pest to local plants or animals, according to the University of Georgia. - photo by Nick Bowman

Joro spiders are here to stay. 

For the past couple of years Joro spiders — which are widespread in China, Korea, Japan and Taiwan — have taken up residence in Northeast Georgia. 

People around Hall County have spotted dozens of these large, yellow-colored spiders along trails and in their backyards. 

Locals aren’t the only ones who have noticed the invasive species, which was first spotted in Braselton around 2014 

Mattias Johansson, assistant professor of biology at the University of North Georgia Gainesville campus, has gathered a group of his students to conduct research on the Joro spider. 

“We don’t really know what their impact is going to be yet, but it’s likely they’re going to have an impact on the ecology around here,” Johansson said. “I suspect that we’re not going to be the only place that has them long because they’re found in fairly different climate areas in Japan, Korea and China.”

Deconstructing a web of information

Since late August, Johansson’s five-student team has collected and observed Joro spiders at Elachee Nature Science Center and Tumbling Creek Woods near the Gainesville campus. They plan to expand their sample range to Athens and sites farther south. 

By collecting the spiders and recording the coordinates and time in which they were found, the students will be able to examine the rate at which their population is growing in the region.

Luckily, for the group of students, Joro spiders aren’t difficult to find. 

Johansson said they build complicated gold-tinted webs that are constructed in layers. They’re also a vibrant shade of yellow, which helps them stand out.

Hannah Cole, who is on Johnasson’s research team, said the task of gathering and storing the samples proves tricky.

Positioning themselves close to the spider, they trap it in a plastic container and then kill it by dropping it in ethanol. 

Through spending hours capturing Joro spiders, Cole said she has noticed how they thrive in open areas on the edge of woods and their odd living arrangements. 

“It’s interesting how close they live together,” she said. “They’re not super aggressive toward one another. They cast out in an open area and sometimes eight different females are all together.”

Johnasson said the only spider species  in Georgia that somewhat resemble the Joro spider are the writing and banana spider. 

Joro spiders stand apart from the others by their larger size and distinctive, multi-layered webs. Many of the females Joro spiders also display a characteristic splash of red on their abdomens. 

“They’re a great spider to do a citizen science piece because they don’t look like any spider around here and they’re giant, especially now getting toward the end of their lifespan. The females are huge.”

Another aspect of the UNG group’s research includes examining their prey items. Through identifying what the spiders eat, Johansson said they draw better conclusions about their ecological impact. 

“We’re curious about what they are eating because they’re incredibly numerous,” he said. “To get a spider where the body is the first joint of your thumb, they’re putting away a fair few bugs that somebody else isn’t going to eat.”

Now that it’s fall, the adult Joro spiders are reaching the end of their year-long lifespan. Johnasson’s team are quickly collecting spiders, prey items and egg sacs, so they will have samples to examine during the winter. 

While the spiders are inactive, Cole plans to examine the genetic differences among the Joro spider populations they’ve observed. She’ll do this by preparing the spider samples for DNA extraction, then she’ll send off the DNA to a lab for analysis. 

“Basically we’re looking for different (genes),” Cole said. “We’re seeing if there’s a mutation. That will help us see if multiple spiders have been coming over at different times or if it was on a single occasion.”

A successful invader 

The Joro spider started popping up in Northeast Georgia around 2014, according to Johansson. 

He said they were first spotted in Braselton. 

“They almost certainly came over on cargo ships and container transport,” Johansson said. “A lot of time containers come on ships and they don’t get opened at the port. They are opened up in their final destination.”

Joro spiders are slowly making their way north. 

The UNG research group uses the app, iNaturalist, to track reports of Joro spiders. The app encourages people to take photos of their wildlife sightings and plot the location. 

Cole said some Joro spiders have been recorded in South Carolina. 

This genus of spiders are professionals at spreading. Johnasson said they use a ballooning technique, in which the spiders spin a web to catch the air current, allowing them to fly for 50-100 miles before latching onto a tree. 

He predicts that the spiders will continue to spread throughout the U.S.

Although they may look big and scary, Johnasson said Joro spiders are not dangerous to people or pets. 

People can kill Joro spiders, but they will always come back because of their widespread numbers.

“People should be aware that these guys live here now and there’s likely to be nothing we can do about that,” Johansson said. “Eradicating them — that’s not going to happen.”

Johansson, whose area of specialization lies with invasive species, said many factors play into the Joro spider’s success at being an invasive species. 

Not only do they adapt to a range of environments, they’re excellent at reproducing rapidly. 

By coming to Northeast Georgia, Johnasson said Joro spiders left all of their enemies behind. This includes parasites, diseases and predators that rely on the spider for food. 

Since Joro spiders aren’t leaving anytime soon and this is a new invasion, Johansson hopes to continue his project with UNG for a long time. He also intends to incorporate his research team’s findings into his classes.  

“To me the joro spiders are a compelling example of an invasive species because they’re huge and bright yellow,” Johnasson said. “Once you start to notice them, you can’t stop.”

Johansson invites the general public to aid his team in locating joro spider populations.

If someone comes across a joro spider, they can send a photo of it and its GPS coordinates to jorospiderga@gmail.com

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