New Jersey is preparing for the arrival of the Joro spider, an invasive species from East Asia. With its striking appearance and ability to travel long distances, this arachnid has been steadily advancing northward through the United States.
The Joro spider, scientifically known as Trichonephila clavata, is notable for its size and vivid coloration. Females can have a body length of about four inches and a leg span reaching up to eight inches, with black and bright yellow banding and a distinctive red belly. Males are smaller and brown in color.
First identified in the United States in 2013, likely arriving via shipping containers, the Joro spider has spread through the southeastern states and has been reported as far north as Maryland. This summer, experts anticipate that these spiders will reach the New York metropolitan area, including New Jersey.
The Joro spider travels using a method known as “ballooning.”
Spiderlings produce silk strands that catch the wind, allowing them to drift significant distances. According to Louis Sorkin, a retired arachnologist from the American Museum of Natural History, these spiders can travel up to 100 miles by this method.
“If the prevailing winds are moving north at this time of year, when spiderlings are the right size to travel in the wind, then they are likely to spread from the South to the New York metropolitan region,” Sorkin explained.
Despite their intimidating size, Joro spiders pose little threat to humans and pets. They possess venom, but it is not harmful to humans. The spiders only bite when provoked. In fact, they can be beneficial, preying on pests such as mosquitoes, yellowjackets, and the invasive spotted lanternfly.
Research from the University of Georgia indicates that Joro spiders can survive in colder temperatures than their relatives, the golden silk spider, suggesting they could potentially thrive throughout much of the Eastern Seaboard. The study found that Joro spiders have higher metabolic and heart rates in cold conditions and can survive brief freezes, making them well-suited to expand beyond the southeastern United States.
While some residents may find the presence of these large spiders unsettling, scientists like Nancy Hinkle, an entomologist at the University of Georgia, view them as beneficial. “This is wonderful. This is exciting. Spiders are our friends,” Hinkle said, noting their role in controlling pest populations.
However, not all experts are as optimistic. Dave Coyle, a professor of forest health and invasive species at Clemson University, cautions that the long-term ecological impact of the Joro spider is still uncertain.
“You really don’t know if this is displacing native stuff or not,” Coyle said. “But I can say that it’s not harmful to people or pets.”
As the Joro spider continues its northward journey, residents of New Jersey and surrounding areas are advised to be aware of their new eight-legged neighbors. While there is no need to actively eliminate them, understanding their presence and potential benefits can help mitigate any initial fears.