As It Happens

This huge, invasive spider may spread to Canada. Here's why you shouldn't panic

The bright yellow and dark blue spider is a timid creature and a known eater of mosquitos and other pests, says University of Georgia ecologist Andy Davis.

The Joro spider is timid, afraid of humans, and likes to eat mosquitos, says ecologist Andy Davis

A new study says a huge invasive spider taking root in the U.S. could eventually show up in Canada. (Submitted by Andy Davis)

Story Transcript

If you're prone to arachnophobia, fair warning: this story is about a big, invasive spider species. 

But even if you are afraid, maybe you should keep reading. Because although the Joro spider is as big as a human palm, and its babies use parachutes to fly kilometres at a time, and it's already invaded the state of Georgia and now could also invade the entire east coast up into southern Ontario, it might not be that bad.

The bright yellow and dark blue spider is a timid creature and a known eater of mosquitos and other pests, says University of Georgia ecologist Andy Davis, who published a study about the species in the Physiological Entomology journal last month.

"Even though this spider sort of looks threatening ... it's really not much of a threat at all," he told As It Happens guest host Gillian Findlay. "Even if you did happen across the web of one of these things and it got tangled in your hair, it would just run away."

Hopped a cargo trip to Georgia 

The Joro spider's body is about size of a grape with eight protruding toothpicks for its outstretched legs, Davis said. 

He says it first arrived in North America n 2013 on a shipping container near Athens, Ga., most likely from their native region near Japan.

"That's one of the things that makes this spider so interesting," he said. "If you think of the climate of Japan, it's very similar to the climate of the U.S. and it's the same latitudes, and so that might be one of the reasons why this spider can do so well here."

The Joro spider, a large spider native to East Asia, is seen in Johns Creek, Ga., on Sunday, Oct. 24, 2021. (Alex Sanz/The Associated Press)

After eight years, the Joro spider population is "exploding" across northern Georgia and spreading into Tennessee, North Carolina and South Carolina.

The study found that after living through the summer and fall, the spider deposits one or two egg sacs before dying. The eggs develop throughout the winter and then hatch in the spring. Once the spiderlings grow big enough, they send a little strand of their silk into the air. 

"This silk catches the air like a parachute, and then they sort of float away," Davis said. "I don't know the exact range that they can float … [but] they can definitely travel some distance."

The Joro spiders couldn't have flown their way across the world to Georgia, but they are great at hitching a ride with cars, Davis said. 

"If we were to wait for them to naturally make it to Canada, it would be 20 years from now," he said. "In the next couple of years … these little pockets of Joros will [probably] end up there and just appear because somebody transported them."

A striking spider with a silver lining

While working on the study, Davis and his co-author discovered how harmless the Joro spider really is.

"It's afraid of humans.... And even if it wanted to, its fangs are pretty small, so it really wouldn't be able to do much," he said.

"In fact, my co-author ... he actually handled a bunch of these for our project and he was actually bitten a couple of times by these spiders. He kind of just shrugged it off and he said it was more like a little pinch."

Andy Davis is a research scientist at the University of Georgia's Odum School of Ecology. (Submitted by Andy Davis)

Their research into the invasive spider's biology and physiology brings up more questions for other studies, such as the spider's impact on local native fauna. But Davis' co-author says there is one thing that's certain: People need to learn to live with these spiders, because they are here to stay.

"The way I see it, there's no point in excess cruelty where it's not needed," Benjamin Frick, co-author of the study and an undergraduate researcher in the School of Ecology, told his campus newspaper. "You have people with saltwater guns shooting them out of the trees and things like that, and that's really just unnecessary."

But when it comes to other bugs, such as mosquitos, the spiders are merciless.

"If you have a bunch of these webs in your yard, you can almost think of it as like free mosquito service," Davis said. "Because these spiders are going to be eating all the pesky bugs in your yard."

Written by Mehek Mazhar. Interview with Andy Davis produced by Sarah Cooper and Chloe Shantz-Hilkes.


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