Joro spiders to spread over East Coast

Joro spiders: Blue and yellow stripes on body of giant spider, yellow patches on black legs.
Do you hate looking at photos of spiders? You’re not alone. Up to 15% of the population has a fear of spiders. Scientists say Joro spiders, like the one pictured here, will soon be prevalent up and down the East Coast. Image via University of Georgia.

According to the website The Recovery Village, arachnophobia – the fear of spiders – is the most common fear in the United States. So prepare yourself. Because scientists at the University of Georgia announced on March 3, 2022, that a new spider – the Joro spider, which arrived in the southeastern U.S. in 2013 – will eventually spread up and down the East Coast. This venomous spider can grow to the size of an adult’s palm. Is your heart racing yet? Take a deep breath, because the invasion of this arachnid species might not be all that bad.

The researchers published their study on February 17, 2022, in the peer-reviewed journal Physiological Entomology.

How Joro spiders arrived, and how they’ll spread

Joro spiders are originally from Japan, but they also exist in China and Korea. They most likely hitched a ride to the United States on shipping containers. Researchers believed they first appeared in the U.S. about 80 miles north of Atlanta. They’ve since spread to many counties in northern Georgia, parts of Tennessee and the Carolinas.

While these spiders can catch a ride on things like shipping containers, cars and luggage, they can also transport themselves on their webs. They fly through the air on a strand of silk in a technique scientists call ballooning. They parachute into new areas to expand their range. It’s how newly hatched Joro spiders spread.

The researchers have accidentally found out just how easy it is for Joro spiders to catch a ride to new locales. Benjamin Frick of the University of Georgia said:

The potential for these spiders to be spread through people’s movements is very high. Anecdotally, right before we published this study, we got a report from a grad student at UGA who had accidentally transported one of these to Oklahoma.

Green counties in a cluster surrounded by white counties in northern Georgia and surrounding states.
The Joro spider originally appeared in parts of Georgia, but scientists expect it to spread up and down the East Coast. Image via University of Georgia.

The cold won’t stop them

These colorful spiders appear to be hardy enough to survive cold temperatures, which will help them spread. As Andy Davis of the University of Georgia said:

It looks like the Joros could probably survive throughout most of the Eastern Seaboard here, which is pretty sobering.

A similar spider, the golden silk spider, arrived in the United States from the tropics more than 150 years ago. But this species wasn’t able to spread outside of the southeastern U.S. Joros, unlike the golden silk spider, have a high metabolism, high heart rate and an ability to withstand cold.

The iNaturalist website and app allows people to record their observations of what they see in the natural world around them. (It led to the discovery of an unnamed grasshopper in 2021.) The scientists looked at Joro reports from iNaturalist and their locations. They also measured the spiders’ heart, metabolic and survival rates during a brief freeze.

They found that the Joro spider has double the metabolism of the golden silk spider. It also has a 77% higher heart rate. Basically, the Joro spider is better equipped physically to survive in colder temperatures.

Yellow and black striped spider holding a caterpillar as a hand holds the web they are in.
This Joro spider has captured a caterpillar in its web. Image via University of Georgia.

Why you have no need to fear

Yes, the Joro spider is venomous, but scientists don’t believe they’re a threat to humans (or pets). Despite the spider’s large size, its fangs are quite small. Their defensive bites most likely wouldn’t even break the skin.

And, despite being an invasive species, they may even be beneficial. The spiders eat insects such as stink bugs, which cause crop damage and swarm in homes. They can help control insects without the use of pesticides. Davis said:

People should try to learn to live with them. If they’re literally in your way, I can see taking a web down and moving them to the side, but they’re just going to be back next year.

Or, as Frick said:

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

Large, drippy webs shine in sunlight.
Watch where you’re walking! Joro spider webs shine when backlit by the sun. Image via University of Georgia.

Bottom line: Joro spiders, relatively new to the United States, may spread across the Eastern Seaboard. These giant spiders are hardy creatures that eat problematic insects.

Source: Physiological evaluation of newly invasive joro spiders (Trichonephila clavata) in the southeastern USA compared to their naturalized cousin, Trichonephila clavipes

Via University of Georgia

Read more: A case against killing spiders

March 7, 2022

Like what you read?
Subscribe and receive daily news delivered to your inbox.

Your email address will only be used for EarthSky content. Privacy Policy
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.

More from 

Kelly Kizer Whitt

View All