It’s a bird – it’s a plane – it’s a parachuting spider the size of your hand?! If you live in the southeastern United States (especially Georgia), you may have already had your first encounter with a joro spider. Consider yourself lucky if you met one of these brightly colored, 6- to 8-nch arachnids and walked away with dry pants.
Joro spiders certainly look intimidating or even terrifying depending on how you feel about spiders, but the truth is they’re nothing to worry about. The more you learn about these curious travelers from Asia, the less you’ll feel the need to pack up and move to Canada. You might even come to appreciate them for their help in the garden.
What Are Joro Spiders?
First things first, what exactly are we talking about here? The joro spider (scientific name Trichonephila clavata) is an invasive species of spider that came to the U.S. from Japan and other parts of East Asia. The species made its debut in North Georgia in 2013, and since then, there have been joro sightings in North Carolina, South Carolina, and Tennessee.
Joros most likely made their way to the U.S. in a shipping container, and they could continue hitching rides with humans to travel across the country – as one researcher found out when he accidentally brought one with him to Oklahoma. Now that they’re on the continent, though, joros have their own special way of getting around.
Joro spiders’ claim to fame is their tendency to “parachute” down from extreme heights. But in reality, what they do is called “ballooning,” and it’s common among orb-weaver spiders. The spider drops from a high elevation and releases a strand of silk as it falls. The wind catches that thread and carries the spider up to 100 miles away from its starting point.
Even though they’ve been here for almost 10 years now, joros have only recently come into the spotlight because of a study published in February 2022 in the Royal Entomological Society’s journal Physiological Entomology.
The study found that joro spiders seem to be more cold-tolerant than their cousins, known as golden silk spiders (Trichonephila clavipes). Golden silk spiders have been in the U.S. for around 160 years, but they haven’t ventured farther than the Southeast because of temperature limitations. The joro spider’s increased cold tolerance could allow it to spread north up the East Coast and beyond, potentially as soon as next year.
What Do Joro Spiders Look Like?
The scariest thing about joro spiders might also be the most fascinating: their colorful appearance. Joros have a bright yellow and silvery-gray banded abdomen, with long black legs encircled by yellow bands. On their underside, you’ll find an interesting black and yellow pattern with some red markings.
What’s most striking, though, is their size – some of them, anyway. Females of the species grow up to 6 to 8 inches wide (including their legs), with an abdomen about the size of a human thumb when it’s full of eggs. Males are considerably smaller and less impressive.
Are Joro Spiders Venomous?
Technically, yes, joro spiders are venomous. But their bite is only intended to paralyze small insects, and their teeth aren’t large enough to penetrate the skin of humans or pets.
That means that even if a joro spider were to bite you, it wouldn’t be dangerous, according to Andy Davis and Benjamin Frick, the entomologists from the University of Georgia who authored the study that’s making waves.
The only time a joro spider bite might cause negative effects is if you happened to have an allergic reaction.
And that’s if they bite you. Like many other spiders, joros prefer to mind their own business in their webs, which are usually around 10 feet off the ground. They won’t attack unless cornered, and they have no interest in invading your home (unlike other spiders often found indoors).
Debunking Fears About Joro Spiders
People tend to panic when they see a big bug, and doubly so if it’s a spider. Add falling from the sky and the potential to spread far and wide, and you’ve got a recipe for nationwide terror.
Take a closer look, though, and the facts aren’t as scary as you might think.
‘Hand-sized spiders raining down from the sky’
Yes, joro spiders can be the size of your hand, and yes, they drop from great heights, but not at the same time. Once the spiders reach their mature size, they’re too heavy for the silken threads to hold. The joros that “parachute” or “balloon” from the sky are younger and smaller, typically only hatchlings.
‘They’re taking over the East Coast’
Fear of joro spiders has spread much faster than the spiders themselves. The recent study suggests that joros might have the capacity to live in colder weather than the golden silk spider, which means they could have the ability to expand beyond the Southeast.
Granted, experts assume that with nothing standing in their way, joros will eventually make their way up the East Coast and potentially all the way to the West Coast. But it hasn’t happened yet, and it isn’t definite. The study compared joros to only one other species of spider and wasn’t necessarily conclusive.
‘Kill them if you see them’
Many people have responded to these imposing but peaceful creatures with violence, going to great lengths to squish them or spray them from afar with saltwater and kill them. However, experts say that killing or removing joro spiders is completely unnecessary.
At worst, joro spiders might annoy you by covering your backyard with spiderwebs. They won’t hurt you, your pets, or even your plants. No evidence suggests that they’ve caused any disruption to native ecosystems of the Southeast. So, there’s no reason not to let them be.
If the webs bother you so much, you can always relocate the spiders away from your property. Although, odds are, if you live where they live, more joro spiders will be back to take their place before long.
Joro Spiders as Gardeners’ Helpers
You actually stand to gain more by letting joro spiders hang around than by getting rid of them, especially if you’re an avid gardener. Like grass spiders and many other spider species, joros are a big help when it comes to pest control.
And joro spiders can be even more effective than the norm. Because they’re so large at maturity, their webs have to be extra strong to hold their weight. Those extra-strength webs can catch more and larger insects, including brown marmorated stink bugs, which most other spiders don’t prey on.
Scientists have found the webs are even strong enough to hold bumblebees and carpenter bees, which is highly uncommon among native spiders in North America. Though that sounds like it could mean bad news for our local bee populations, joro spiders’ impact on native species has been insignificant so far.
But their impact on keeping your garden pest-free could be huge!
The Final Verdict on Joro Spiders
Long story short, joro spiders are harmless. If you were expecting the next black widow or brown recluse, you would be mistaken.
Joros won’t hurt you, your pets, or your plants. In fact, they can benefit your garden by controlling the insect pests that would feed on your plants. Though it’s true that they might spread across the U.S. in the next few decades, there’s no reason to fear.
Now is the perfect time to face your arachnophobia head-on by cohabitating peacefully with joro spiders. They might seem like something out of your nightmares, but in reality, they’re more like a gardeners’ dream.
Main Photo Credit: The Nature Box / CC BY-SA 4.0 / via Wikimedia Commons