Your Questions About the Joro Spider, Answered

Alarm over the possible arrival of the Joro spider in the greater New York City area has sparked concern across the Northeast over the scary-looking eight-legged creature. But experts are advising residents to stay calm, calling the arachnid harmless and also questioning both whether and when the spider will arrive up north. 

“There's no reason to panic for this,” David Coyle, an assistant professor in the Department of Forestry and Environmental Conservation at Clemson University, tells TIME. 

The yellow and gray-colored arachnids are originally from east Asia. The creatures were first documented in the southeastern U.S. around 2013, but Coyle says it's also possible that the spider arrived as early as 2010. Experts guess that the arachnids likely hitchhiked on cargo containers traveling to a town north of Atlanta. 

Joro spiders are an invasive—meaning nonnative—species. In the U.S., the creatures mostly reside in North Georgia, the Appalachian region of South Carolina, the far west corner of North Carolina, and the far southeastern corner of Tennessee. Joro spiders have also been recorded as far north as Baltimore, according to inaturalist.org. 

The spiders are around the size of a woman’s hand, with a body up to an inch long, and a leg span of up to four inches. Despite their size, experts say they are harmless. “In areas where the populations are high—are they annoying? Absolutely. They're everywhere and their webs are huge,” says Coyle. “But in terms of danger, we haven't seen anything like that.”

Here’s what to know about the spider. 

Will the spider actually reach New York City? 

While it is possible the Joro spider could travel to New York City, it would have to reach the metro area through some sort of human-aided movement. 

“In terms of if or when [the Joro spider] will get there, we have no idea. It could be a year, could be a decade—there's really no way to tell. On its own, it's not really traveling that far,” says Coyle. “[But] there's always the possibility of a hitchhiking population, which is probably how that little spot up by Baltimore got started.” 

Coyle notes that it would only take a group of the spider’s egg sacks to be transported from one location to the next for the spider population to take root in another state. Still, experts say that any estimates on timing would be pure speculation. Andy Davis, a research scientist at the Odum School of Ecology at the University of Georgia, adds that even if there were a few reports of the spiders in New York, it would still take years for the number of spiders to become a viable population. 

It’s still very possible for the creature to live in a place like New York based on their physiology. “If you look at their native range in East Asia, it's a very big range with a large degree of latitudes from northern Japan all the way down to Taiwan,” says Davis. “If you extrapolate that, that means these fighters could probably live in a place like Maine or South Florida if they wanted to.”

Does the Joro spider fly? 

Joro spiders do not fly—or at least, not the way some people might be picturing it. Coyle says that younger Joro spiders do travel by air when they are spiderlings. “Some of them will kind of get up on a high perch, and they'll let a few strains of silk go, and some of that silk is going to get captured by the wind, and they're going to get blown away,” he says.  It's a common process known as ballooning.

By the time arachnids get larger, however, they are not able to float around in the air.

Courtesy of David CoyleJoro spider

Is the spider harmful to humans or pets? 

Experts say the Joro spider does not pose a risk to humans or pets. “They have venom just like any other spider does,” says Davis. “But as long as you leave them alone, they'll leave you alone.” Part of that has to do with the personality of the spider, which experts describe as fairly docile and shy. Even if a person were to get bitten by a Joro spider, Coyle says that it is akin to a mosquito bite, while Davis compares it to more of a bee sting.

Pets will also likely be safe around the species. Joro spiders spend a majority of their time in webs above the ground, per Davis, which is probably too high for a cat or dog to reach. Even then, any sort of attack by the spider would have to have been provoked. 

“They would prefer to not bite you because from a biological perspective, producing venom for anything really costs a lot of physiological  energy,” says Coyle. “They're really only going to bite if they're completely trapped as a last defense mechanism.”

Is the spider harmful to the environment?

Experts are not sure about the Joro spider’s impact on the environment. The critters are not comparable to spotted lanternflies, which experts encourage people to kill because they are a danger to more than 100 trees and plants.  

The Joro spider, however, does not harm any vegetation. Experts are mixed on how they affect native species of spiders. Davis says that Juro spider webs have been seen next to native spider webs, which means the two can coexist. “What could be happening is that the Joro spiders are out-competing some of our native spiders for food, because they're both going after the same food,” says Davis. “But on the other hand, Joro spiders could end up becoming a food source themselves for somebody else, by some of our birds, or their egg cases could be a tasty snack for a raccoon in the winter.” 

Coyle says that in areas with a high population of Joros, there are not as many native spider species seen, though it is not clear what would keep the differing types of spiders apart. 

Davis says it's not necessary to kill the spider, though Coyle says that people can squash the arachnid if that makes them the most comfortable. “Are you going to make any measurable impact on the populations? No. But if that's your thing, go for it,” he notes.