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    • Exotic joro spider discovered in the Smokies
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    Exotic joro spider discovered in the Smokies

    Online Niel Posted on

    Holly Kays
    | Word from the Smokies

    Depending on your perspective, seeing a giant spider (Trichonephila clavata) for the first time is either an exhilarating experience or an alarming emergency. These creatures are stunningly beautiful, their bodies wearing an intricate pattern of black, white and yellow, sprinkled with a dash of red. But they are also strikingly large. While males remain much smaller, females can reach a leg length of up to four inches, their bodies more than a quarter of that length.

    Native to Asia, orb spiders have been living in the United States since at least 2013, when they were spotted in Georgia between Athens and Atlanta. They were SPREAD since then, and on October 17th, Great Smoky Mountains National Park recorded its first sighting of a gypsy. Jarren Rendon, an AmeriCorps intern with the park’s Vegetation Management Branch, spotted it just west of Hyatt Lane in Cades Cove while working to remove exotic vegetation from the area.

    Park entomologist Becky Nichols said that while the find was noteworthy, it was not surprising. The presence of the spider in western North Carolina was first recorded on iNaturalist in 2021, with multiple sightings in eastern Tennessee in 2024. An October 2023 sighting placed the spider just outside the park boundary south of Fontana Lake near Bryson City, and on September 8, an iNaturalist user documented the orb spider in Townsend, Tennessee.

    “It’s right down the road from Cades Cove, so it’s no surprise, really, that it was found there,” Nichols said. “We’re not sure how long it’s been there, but we’d expect to see them in the park at some point.”

    Earlier this year, park partner Discover Life in America added the joro spider to Smokies Most Wanted list. Park visitors who spot one of these species can upload their observations to iNaturalist and help scientists better understand their prevalence in the park.

    “It’s good to have an idea of ​​where it is in the park so that as it’s studied, if we learn more about the potential harm it could do to our native species, we have a better idea about where to go if we have to work on control measures,” said Will Kuhn, director of science and research for DLiA.

    Now that the spider’s presence has been verified inside the park, Nichols is considering what type of research or monitoring efforts the park should undertake as it continues to spread.

    “It’s something we’re going to keep our eyes on, like any potentially invasive species that could impact the ecosystem,” Nichols said. “And we’ll be paying close attention to studies looking at the ecological impact of this spider to determine if we need to take management action, I don’t suspect we will, but we’ll just have to wait and see.”

    Andy Davis, a research assistant at the University of Georgia’s Odum School of Ecology, has studied the recluse spider for years as it proliferated in northeast Georgia and beyond. He said “the jury is still out” on the spider’s potential impact on native species, but that early indications are that it “isn’t even in the same category” as highly destructive invasives like spotted lanternfly. Native to some of the same areas as the orb spider, the spotted lanternfly has proven so damaging to native ecosystems that it has become overrun that people living in these areas have been trained to kill them on sight.

    “Joros are a nuisance to people, for sure, but it’s hard to see any real damage being done compared to something like the spotted lanternfly,” Davis said.

    However, a 2023 article published in “Ecology and Evolution” provided evidence that joro could harm native spider species. The researchers found that the recluse was the most abundant spider in half of the study sites where it was present, and that the diversity of native blind weavers was lower in sites where the recluse had been present the longest. Although “human population density complicates this finding,” the researchers wrote, their results indicate that the joro “is an invasive species and deserves much more ecological analysis.”

    More research is needed on this topic, but so far, the most obvious impact of the joro spider is the intensity of its presence. They are large spiders that live comfortably in highly disturbed urban environments, including porches, decks, gas pumps, and busy intersections, so they are usually easy to spot.

    “Here in Georgia, where we have recluse spiders everywhere, you often see them next to native spider webs, and they seem to coexist, anecdotally, anyway,” Davis said.

    What is clear is that joros are not exceptionally aggressive spiders – quite the opposite, in fact. Davis, whose research focuses on animal physiology, wrote a paper in collaboration with one of his students, which was published in the scientific journal “Arthropoda” in May 2023, showing that orb spiders are “extremely shy” compared to other spider species. All spiders exhibit freezing behavior when faced with a threat, and how long they stay frozen indicates how shy or aggressive they are. Of the 10 spider species observed for the study, most remained motionless for less than a minute after being threatened, but the recluse spider remained frozen for more than an hour, making it “one of the shyest species of spider ever documented,” Davis said. .

    “I’ve had these things crawl up and down my arms and they seem to be well handled,” he said.

    The full extent of the hornet’s potential impact on native ecology remains unknown, but scientists are working to color the picture. Davis points out that while recluse spiders may compete for food with native spiders, they themselves are also a food source for other species, including birds. There is also some hope that joro spiders could serve as a mild control over other invasive species that come from the same area of ​​Asia where the joro is native. The recluse spider is one of the few creatures known to eat the brown marbled spider, for example, and while its range in North America does not currently overlap with that of the spotted flyer, there have been documented cases of recluse spiders eat the butterfly in their native Asia – although species native to North America will also eat this insect.

    “If there’s any good news here, it’s that orb spiders are good at eating these creatures,” Davis said.

    However, orb spiders also seem to have an intuition about species to which they have not been historically exposed. One study published this year in “Insects” Davis and his students found that orb spiders, whose native range does not overlap with that of the monarch butterfly, still avoid eating the insect, whose diet of milkweed larvae makes it unpalatable to predators. In the study, spiders attacked monarchs only 20 percent of the time when butterflies were thrown into their webs, compared to 85 percent of the time for bay fritters and 58 percent of the time for tiger swallows, both of the same size . or greater than monarchs.

    “In some cases, they will actually cut monarchs off their web,” Davis said. The study states that this result “raises many questions” about how spiders perceive monarchs as unpleasant without having eaten them first.

    Sometimes other creatures benefit from the joro spider’s catches. In 2022, Davis spoke with National Geographic after hearing from a man in Atlanta who saw a female cardinal land on a joro spider web and start scooping food out of it. The sighting is a testament to both the strength of the orb webs and the unlikely relationships the spiders can form with other species as their populations grow.

    Eventually, joro is likely to spread to the United States and perhaps even Canada. The species is tolerant of human disturbance and often manages to hitchhike with motorized vehicles, and Davis’ research shows that it is more cold tolerant than similar species, as evidenced by a paper 2022 published in “Physiological Entomology”. Another group of researchers published a paper in the September issue of the “Journal of Asia-Pacific Biodiversity” projecting that the spider’s range could one day extend as far north as southern Canada and as far south as the Gulf Coast.

    This prediction does not sit well with people who are not thrilled at the prospect of such large arachnids taking up residence outside their homes. But Davis said the spiders are not dangerous and may even provide an opportunity for their human neighbors.

    “Because joro spiders are so docile and because they are so sedentary and because they live so close to people,” he said, “you can get to know that spider and use it as an educational tool. the opportunity to show children what spiders do to survive in the natural world.”

    Holly Kays is the lead writer for the 29,000-member Smokies Life, a nonprofit organization dedicated to supporting the scientific, historical and interpretive activities of the Great Smoky Mountains National Park by providing educational products and services such as this column. Learn more at SmokiesLife.org or reach the author at [email protected].

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