Rumors of the giant flying Joro spider, landing in New Jersey this summer never materialized in the Garden State. But they did land in Philly's backyard.

On Sept. 5, a Joro spider was found in Ivyland, Pa., a Bucks County borough nearly 30 miles north of Philadelphia, in the yard of someone's home. The sighting was confirmed by a site visit from a local entomologist, according to the University of Georgia's Center for Invasive Species and Ecosystem Health. The center tracks invasive plant, insect, and wildlife sightings, including the Joro spider, across the U.S. While there have been many sightings of spiders that look almost identical to the Joro reported in Pennsylvania as early as June, this is the first to be confirmed.

"There were six individual spiders found in the same area, that turned out to be other spider species. Since these spiders (including the Joro spider) were all found in the same location in Pennsylvania, it's likely that they were accidentally brought to the area as eggs or a pregnant female spider on a vehicle, boat, camper, or other item," said Pennsylvania State University arthropod identification expert Michael Skvarla. "If the spiders in the area are eliminated this year, that may be enough to eliminate them from Pennsylvania until they are accidentally introduced again at a later date."

The bad news is that they're here to stay in the U.S. after establishing themselves in Georgia in 2013, and scientists don't know what kind of damage they will do. The good news is that Joro spiders don't pose a threat to humans or household pets, Skvarla said.

"They're not very venomous at all, and they're very reluctant biters," he said. "Even if you pick them up, they might bite in defense if you grab one, but the fangs are so small that it's hard for them to pierce human skin despite their large size."

What is a Joro spider?

Joros, or Trichonephila clavata, are large brightly colored spiders that can fly using a technique called "kiting," where a Joro shoots silk webs into the air and uses them like balloons to travel.

"Based on previous estimates, Joro spiders can move around 10 miles per year if they are unassisted. However, human-mediated movement can move them much further, much faster," Skvarla said.

Female spiders are bright yellow and black, growing up to four inches (the common house spider is smaller than a quarter-inch), and spin webs up to 10 feet wide. Male spiders are smaller, brown-colored, and can't spin webs. Females can lay a single egg sac containing 500 spider eggs.

In Japanese, joro spiders are known as joro-gumo, which translates to "entangling or binding bride," according to Penn State Extension.

Do Joro spiders bite humans or pets?

Joros will only attack if the spider feels attacked or provoked. If bitten, there won't be severe symptoms, unless a person is allergic to spider bites. Typically, a Joro spider bite feels similar to the sting of a yellowjacket wasp, Skvarla said.

Are Joro spiders an invasive species?

While it's not yet known how Joro spiders impact the ecosystem, they are native to China, India, Japan, North and South Korea, Taiwan, and Vietnam, and are considered invasive in the U.S. However, early observations by UGA scientists suggest that Joros can coexist with other orb-weaving spiders, sometimes even spinning a web close to or attached to another spider's web.

Should you kill Joro spiders?

Just like the spotted lanternfly, local residents should stomp or kill the Joro spider when spotted, but not before taking pictures of the spider and reporting it to the Penn State Insect Identification Lab or UGA's invasive species tracker.

"Since Joro spiders are not native and not widely established here, the best course of action is to kill them when they're found," Skvarla said. "That said, there are important native spiders that may be mistaken for Joro spiders, such as yellow garden spiders. So readers should verify the identity of any spider before killing it to avoid killing native species by mistake."

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