Have You Seen This Spider?
By Carol Clark
Dr. Mattias Johansson, assistant professor of biology at the University of North Georgia in Gainesville, saw his first Joro spider in the Chicopee Woods Nature Preserve. He was hiking with Lee Irminger, Elachee Nature Science Center’s natural resources manager, chatting about the flora and fauna, when Irminger pointed out the flamboyant Asian arachnid.
“These spiders are really distinctive, because of their large size and their yellow-and-black-striped legs,” Johansson says. “The more you look for them, the more you notice them and how common they have become in our area. I find them fascinating.”
Johansson’s research focuses on biodiversity. He uses genetic tools to understand the population distributions of native species and the global spread of invasive species. Nephila clavata, more commonly known as the Joro spider, is one of his latest study subjects.
An East Asia native, N. clavata is common in Japan, Korea, Taiwan and China. The first North American report of a Joro spider occurred near Athens, Georgia, in 2014. Other specimens were soon collected from sites in northeast Georgia and the spider appears to be thriving in its new habitat. They are believed to have arrived in, or on, shipping containers from Asian ports. From coastal entry points they may have “hitchhiked” inland via shipping containers that were loaded onto trucks and trains for transport.
Johansson and his students have been collecting specimens of the spider from Chicopee Woods Nature Preserve and elsewhere and conducting genetic analyses of them. They are mapping locations of the spiders and using population genetics to learn more about how they are spreading.
Hannah Cole, pictured left, is joined by fellow UNG researcher Gabriella Lupica, to collect Joro spider specimens.
“We’re basically looking at how connected one population is to another,” Johansson explains. “Genetics can help us answer questions like whether there were multiple introductions of the spider to Georgia, and in different places, or if they were all introduced at the same place and time.”
Citizen Sightings: You Can Help
Johansson is now launching a citizen science project, asking people who spot the spiders in their yards, while hiking, or elsewhere, to report it via a special email address: email@example.com.
“The ideal report would consist of a photo taken with the camera’s location data turned on,” he says. “We’re looking for clues about where to go to find more specimens. Among the questions I’m interested in is are they just spreading northwest-wards from Athens or in all directions? And where do they run out of gas, in terms of their spread?”
The strangest report so far came from one of Johansson’s students, who found a Joro spider on the door handle of her car as she was about to grab onto it. “She made a video of it and sent it to me,” Johansson says. “She said if she was late to class, it was my fault.”
Tips for Spotting a Joro Spider
The Joro spider is hard to miss. The females, which are four times as big as the males, can have a leg span of three to four inches. They reach full maturity in the fall, Johansson says, as they prepare to lay their eggs. The females have bluish-green strips on their yellow backs and red markings on their undersides, in addition to black legs vividly striped in yellow. The males are mostly a dull brown.
Despite its fearsome appearance, the Joro spider is not particularly poisonous or harmful to humans.
N. clavata are part of a genus of spiders known as golden orb-web weavers. “The webs of this genus of spiders are incredibly strong,” Johansson says. “They’re being studied for both their web-spinning ability and what proteins they use to make their silk.”
The Joro spider is spinning webs right across the hiking trails of Chicopee Woods, spanning as much as five feet across. Their webs glint a golden yellow in sunlight and are not just a single layer, but have an elaborate three-dimensional structure.
“Their mating season is beginning now [September],” Johansson says. “I saw a female attended by three males in her web. She was chasing them around and they were kind of staying out of her way.”
This sort of behavior could explain some of the mythology around the spider. In Japanese folklore, it is described as a shape-shifter that preys on young men — its Japanese name “joro-gumo,” means “binding bride.” In Korea, the spider is called “mudang gumi,” or the “fortune-teller” spider.
The spider’s eggs will overwinter and hatch in the spring. The babies, or spiderlings, put out a single thread of silken web material. “The silk thread acts like a balloon and a parachute,” Johansson explains. “They fly off and then land in new places.”
Johansson’s research complements other ongoing work about this relatively new arrival in the state, including a study at the University of Georgia.
While it’s possible for a species to become established in a new area without a noticeable impact, they can also cause serious ecological and economic problems. “It’s important to learn what we can about invasive species, so that we might be able to prevent new introductions or mitigate their spread,” Johansson says.
It’s not yet clear what impact the Joro spiders may have. “They’re big and they eat insects, so that could be an issue for the native spiders competing with them, as well as for the local insect community,” Johansson says. “And if they’re eating a lot of pollinators, that could be an issue for the plant community.”
Research in Chicopee Woods
Johansson sits on Elachee’s recently formed Science Advisory Board which was created to connect experts with research opportunities within the Chicopee Woods Nature Preserve and to help develop land management advice. This research supports Elachee’s natural resource land management activities within the Preserve by developing further understanding of the Joro spider.
This study is one of many underway by research teams from the University of North Georgia. Elachee recently reported on a study that will ultimately lead to discovery and insight that will shape perceptions of the geologic history of the region. Read What Rocks Reveal.
Elachee Nature Science Center utilizes the Chicopee Woods as an outdoor classroom and is responsible for land management of this north Georgia forest as its Trustee in perpetuity, under the authority of the Chicopee Woods Area Park Commission. Here Elachee collaborates with community partners and volunteer corps to build, maintain and ensure a sustainable legacy. This conservation stewardship work restores and protects the health of its forest, streams and habitats, in addition to responsibility for ongoing maintenance of the Nature Preserve’s extensive hiking trail system.
To learn more call 770-535-1976 or visit www.elachee.org.