5 Things To Know About Giant ‘Flying’ Joro Spiders In A Dozen States

ACROSS AMERICA — Calm down, the rapid spread of the giant “flying” Joro spider to much of the East Coast is hardly apocalyptic.

Yes, a spider that looks like it’s flying through the air is the stuff of arachnophobe nightmares. Yes, they have expanded far beyond Georgia, where they were discovered in 2013 after likely hitching a ride in a shipping container from the Far East. And, yes, the invasive spiders seem to be adapting so well in the United States that people who encounter them may have to similarly adapt and learn to live with them, according to experts.

Still, the Joro spider “sort of checks all the boxes for public hysteria.” David Nelson, a professor of biology at Southern Adventist University who has studied the arachnid’s growing range. “My sense is people like the weird and fantastic and potentially dangerous.”

Joro Watch, a citizen science monitoring program created by the University of Georgia’s Center for Invasive Species and Ecosystem Health, helps researchers understand the spiders’ spread. In only about a decade, Joro spiders have spread from a single state, Georgia, to Alabama, Florida, Kentucky, Maryland, Mississippi, North Carolina, Pennsylvania, South Carolina, Tennessee, Virginia and West Virginia. One even hitched a ride to Oklahoma with a Georgia State University researcher.

Researchers have found that Joro spiders have a high enough metabolism to survive the colder temperatures that kill off many of their arachnid cousins. They’re expected to spread into even more states, particularly in the eastern U.S. where living conditions are more favorable.

Below are five things to know about Joro spiders, or Trichonephila clavata, part of a group of spiders known as orb weavers for their highly symmetrical wheel-shaped webs.

They’re Venomous But Timid

Let’s get this out of the way: Although adult females can grow as large as a woman’s hand, these creatures are all legs and no bite when it comes to humans.

Like all spiders, they inject venom into prey captured in their webs. It’s pointless and they have no interest in injecting venom into people and their pets. Joro Watch researchers also say there are no recorded incidents in which the spiders have bitten a human.

“From our experience collecting hundreds of these spiders, having them in our hair and wandering on our arms, and interacting with thousands of webs, they have not bit,” Joro Watch says. “In general, these spiders are timid and non-aggressive, so the likelihood of being bitten is low unless provoked needlessly.”

Do Joros Actually Fly?

Wingless Joro spiders don’t fly but travel on a breeze. Using a technique called “ballooning,” young spiders make silk webs that act as a parachute that lifts them into the atmosphere and carries them at the speed of wind.

If the silk is long enough, Joros can travel up to 100 miles at a time, though it’s more common for them to travel only a few miles. Where they end up can be at the fate of the wind.

According to Joro Watch, it’s more likely the spiders spread so quickly because people are unknowingly moving their silk-covered eggs in their cars, luggage, and along with various goods and cargo.

Don’t Squish Them, Report Them

Unlike some other invasive species that have found their way into the United States in shipping containers, including spotted lanternflies and brown marmorated stink bugs, Joro spiders don’t seem to pose an environmental or economic threat.

“The way I see it, there’s no point in excess cruelty where it’s not needed,” Benjamin Frick, a Georgia State University researcher who co-authored a study on the Joro’s range, said in a 2022 news release.

“There’s really no reason to go around actively squishing them,” Frick said. “Humans are at the root of their invasion. Don’t blame the Joro spider.”

Still, the Joro spider is a non-indigenous, invasive species, and scientists still have much to learn about how it will behave in a new ecosystem and its potential to cause economic or environmental harm, or harm to human health.

People who see a Joro spider are encouraged to a take a picture and report it to Joro Watch, either through the website or the EDDMapS app.

Male and female Joro spiders look very different. Adult females are much larger and are brightly colored with yellow, blue-ish and green horizontal bands, and also have a large red mark on the bottom side of their abdomen. Their legs are black with yellow-orange bands. Males are much smaller and more muted in color. To be sure it’s a Joro and not a look-alike, visit Joro Watch’s Species Info page for images and descriptions.

Citizen scientists who go out looking for Joros but don’t find them should also report that, too. Joro Watch says it’s just as important to know where they haven’t become established as where they have because that information can help scientists better understand their needs and behaviors.

No ‘Skeeters’? Thank A Joro

It could be that Joros are more beneficial than harmful. They will eat whatever lands in their webs. That includes stink bugs, yellow jackets, mosquitos, flies, cockroaches — although they’ve also been known to capture and eat beneficial insects such as bees, butterflies and dragonflies.

In rare instances, hummingbirds have gotten caught in the spider’s webs, but to date, there have been no published reports or articles about other birds or bats getting caught, according to Joro Watch. Although the webs are strong, hummingbirds and bats are most likely to fly through them

“Joro spiders can be incredibly important in reducing pests,” Michael J. Raupp, a University of Maryland professor who specializes in entomology studies, told ABC News.

Still, it’s unlikely that Joro spiders are an effective weapon against tree-killing spotted lanternflies that are taking hold along the East Coast, as some observers have suggested, according to David Coyle, an assistant professor at Clemson University who was part of a team researching the Joro’s range for a study published in November last year.

They might eat a few, Coyle told PBS, but there’s “zero chance” they’ll even dent the population.

Joro Spiders Are Hip To Urban Life

It turns out the orb-weaving spiders are hip to the urban lifestyle and have developed a tolerance for vibrations and loud noises, according to researchers at the University of Georgia. That means they can live near busy roads and in places that most other animals avoid.

Interestingly, the University of Georgia researchers found that although Joro spiders rarely attack unless provoked, urban Joros are even more chill.

In more than 350 trials, researchers used a tuning fork to mimic the vibrations of prey, Joros in busy urban locations attacked half the time, while those in less populated places were more aggressive and attacked 65 percent of the time.

The researchers noted the spiders were all about the same weight, indicating those in more populated areas have adapted to different food sources and environmental conditions, spinning their orb-like webs between power lines, on stoplights and other stationary objects.