Arachnophobes, beware—there's a giant invasive spider potentially heading to the tri-state area this summer.


Joro spiders may start appearing in Pennsylvania, New Jersey, and Delaware, spreading north from the southeastern U.S., where they've been proliferating.


Native to East Asia, these yellow and black arachnids have been in Georgia for about a decade. A peer-reviewed study in fall 2023 by David Coyle, an assistant professor at Clemson University, concluded that the species is "here to stay" in the U.S., spreading rapidly across the country.


By October 2022, the Joro spider's range covered at least 120,000 square kilometers across Georgia, South Carolina, North Carolina, and Tennessee, with sightings in Alabama, Maryland, Oklahoma, and West Virginia. They are expected to continue spreading along the East Coast.


“This spider is likely to inhabit most of the eastern U.S.,” Coyle said. “Their comfort area in their native range matches up well with much of North America. Barring unforeseen circumstances, we expect their range to expand, especially northward, with populations already in Maryland.” These spiders can travel by "ballooning," releasing silk threads to catch the wind, allowing them to spread easily.


### What to Know About the Joro Spider

#### Appearance and Size

Female Joro spiders (Trichonephila clavata) have bodies about 1 inch long and leg spans up to 4 inches. They are brightly colored, while males are brown. Despite their size, they are relatively harmless to humans and pets.


#### Potential Arrival in the Delaware Valley

The arrival of Joro spiders in the Delaware Valley is possible but not imminent. According to a 2022 Penn State Extension article, the spiders could spread throughout eastern North America, potentially reaching Pennsylvania. They have been spreading outward at about 10 miles per year, meaning southeastern Pennsylvania could see them in 35 years, with northwestern Pennsylvania in 60 years. However, ballooning and human-mediated transport could accelerate their spread.


Pennsylvania wildlife officials have not confirmed immediate sightings but suggest checking Penn State Extension for updates. New Jersey and Delaware officials also have no current involvement in tracking these spiders. University of Delaware entomologist Dr. Doug Tallamy downplayed the potential invasion, saying it’s low on the list of concerns.


#### How Did Joro Spiders Get to the U.S.?

Joro spiders likely arrived in the U.S. via shipping containers from East Asia.


#### Orb-Weaver Family

Joro spiders belong to the orb-weaver family, known for spinning large, orb-shaped webs. They resemble garden and banana spiders.


#### Do They Fly?

Joro spiders spread primarily through natural dispersal mechanisms like ballooning, using silk threads to catch the wind. Human-mediated transport also contributes to their spread.

#### Are They Dangerous?

Though they may seem frightening, Joro spiders are relatively harmless to people and pets. A University of Georgia study found them to be shy, rarely biting, and unlikely to pierce human skin. They prefer to spin webs outside rather than inside homes. If a Joro spider needs to be moved, using a broom or stick is recommended.


#### Diet

Joro spiders are not picky eaters, consuming mosquitoes, yellowjackets, stink bugs, and even spotted lanternflies. They indiscriminately eat whatever gets caught in their webs, including rare native pollinators.


Coyle's study revealed that Joro spiders displace native species and have other negative impacts, although the reasons are unclear. "These spiders are pushing out native species and catching whatever gets in their webs,” Coyle said. “Their impact is nuanced and depends on perspective.”