Will Joro spiders spread across the United States or stay isolated to the Southeast?
The debate about whether or not Joro spiders will find their way outside of the Southeastern United States is up for debate. In this author’s opinion, the spread of Joros in the United States will likely happen over the next decade. Unlike their not-so-distant cousin, the Golden Silk Spider or Trichonephila clavipes, there is evidence showing that Joro spiders will eventually make it out of the Southeastern United States. Comparing the two species will help researchers determine the fate of Joros here.
Do Joro spiders survive in Winter?
Joros don’t like the cold, but unlike the Golden Silk spider, the majority of Joros (up to 74%) can survive a brief freeze, where only 50% of Golden Silk spiders can survive. Despite their tolerance to cold weather, the adult spiders will likely die off in winter.
In Japan, Joros can survive winters with average temperatures 32°F, Pennsylvania’s current average winter temperature. This suggests that Joros should be able to reach Pennsylvania before they are stopped by the cold.
What makes Joros different from “golden silk” or “banana spiders?”
Along with their cold-tolerate nature, they also have a shorter life cycle than “golden silk spiders,” meaning they don’t need to survive as long in order to reproduce. Joros also have a higher metabolism, consuming more in their wake than other spiders of their kind.
Their webs are very sturdy and strong, and have even resulted in some Georgia residents to take extreme measures in their effort to remove the webs.
What is “ballooning” and why is everyone concerned about it?
Of the 2000+ invasive insect and arachnid species in North America, the Joro spider is one of the latest new inhabitants. Alongside their extreme survival skills and strong webs, they also have the ability to spread quickly through “ballooning.”
Ballooning happens in spring after the spiders hatch from their egg sac. During this phase of their life, they are lightweight and can easily become airborne. This allows them to quickly move between locations via the air stream in the area, by about 10 miles each year. It has been noted that Joros, and other Nephilas, are great at dispersing themselves through ballooning.
Aside from ballooning, how else can Joros spread?
As more and more Joros make their home in Georgia and other southern states, the probability that they will begin to spread to other areas by latching on to cargo and travel vehicles is high. If a female were to secure an egg sac, containing upwards of 500 eggs, to a shipping container, then the spread of Joros could impact the new area or any of the stops along the way, depending on the time of year of the shipment. Depending on the time of year, a female full of eggs that attaches herself to a transportation vehicle could easily spread Joros to her new home.
While the future of the Joro spider is still up for debate, evidence shows that we will be dealing with them for the foreseeable future. Gaining a better understanding of this invasive creature will help us combat the environmental consequences of their existence in the United States.
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Reference List:
National Library of Medicine. (2015, February 5). Nephila clavata L Koch, the Joro Spider of East Asia, newly recorded from North America (Araneae: Nephilidae). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4327315/
Royal Entomological Society. (2022, February 17). Physiological evaluation of newly invasive jorō spiders (Trichonephila clavata) in the southeastern USA compared to their naturalized cousin, Trichonephila clavipes. https://resjournals.onlinelibrary.wiley.com/doi/10.1111/phen.12385