Millions of Joro spiders will parachute out of the sky this spring

Millions of Joro spiders are expected to colonize the entire East Coast this spring. The spiders will literally drop from the sky, using their webs like parachutes. The invasion is predicted to begin in May, and while it may sound terrifying, experts say we have nothing to fear.

Joro spiders are large spiders with bright blue and yellow striped bodies and black and red legs. The spiders are native to most of Japan but arrived in the United States around the year 2013. Gaining a foothold in Georgia, Joro spiders have spread throughout the southeastern US. 

With their colorful bodies and the golden silk they produce, Joro spiders are easy targets for human aggression. However, unlike some other non-native species, Joros do not seem to cause any harm. In fact, the spiders may possibly provide another food source for birds and are fairly harmless to people and their pets. 

Unless directly threatened. Joro spiders do not bite. When they do, their fangs are often too small to pierce human skin. New research from the University of Georgia suggests that the spiders are just beginning their spread throughout the US. 

“People should try to learn to live with them,” said study co-author Andy Davis. “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.”

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

The research compared the physiology of Joro spiders with the golden silk spider, which arrived in the US from the tropics about 160 years ago. The study showed that the golden silk spiders have remained in the southeast because their low metabolisms and slow heart rate leave them vulnerable to cold. The same can not be said for Joro spiders with heart rates 77 percent higher. 

“Just by looking at that, it looks like the Joros could probably survive throughout most of the Eastern Seaboard here, which is pretty sobering,” said Davis.

The spiders can move around by ballooning a ride on air currents using their silk. Just as likely, they may hitch a ride with people on cars, planes, anything that moves. 

“The potential for these spiders to be spread through people’s movements is very high,” said Frick. “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.”

Even though a future where Joro spiders live throughout the eastern US is a very real possibility, the authors caution that it’s no reason to fear. Actually, if we are to find blame we should just look in the mirror. 

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

The study is published in the journal Physiological Entomology.

Image Credit: UGA/Submitted Photo

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By Zach Fitzner, Earth.com Staff Writer