Is the Joro Spider Venomous? Numbers of Large Invasive Species Explode in Georgia

Sightings of the Joro spider, a large, invasive species that was spotted in Georgia for the first time less than a decade ago, are on the rise in the state.

The spider is distinctive not only for its size, with individuals measuring approximately three inches across, but also for its striking colors.

Bright yellow, orange and black stripes criss-cross their legs, while their bodies are predominantly yellow with dark blue and red markings.

They also weave enormous orb webs from their equally bright yellow silk.

This vibrant color scheme, as well as the fact that the Joro spider is an invasive species, may tempt people into thinking that it could be dangerous to humans.

However, unless you're specifically allergic to Joro spider venom, a bite from the species is considered to be harmless to humans.

"All spiders have venom that they use to subdue prey," Byron Freeman, director of the Georgia Museum of Natural History, has said.

"If you put your hand in front of one and try to make it bite you, it probably will. But they run if you disturb their web. They're trying to get out of the way."

The first confirmed sighting of a Joro spider in Georgia came in 2013, and it has since spread across the state and has even been reported in neighboring North Carolina.

Native to Japan, Korea, China and Taiwan, experts have only been able to speculate about how it came to the U.S.

It's likely that a cluster of Joro spiderlings arrived in Georgia on a shipping container. It's also possible that they could eventually venture beyond the Deep South and into more northern territories, with the Joro spider capable of withstanding colder weather.

The spiders reach maturity in early November, and each of their egg sacs can contain hundreds of offspring.

They also spread by ballooning, which they do by spinning silk threads specifically designed to catch the wind and transport them elsewhere.

Any arachnophobes in Georgia who are concerned about the emergence of the spiders may be pleased to learn that they tend to die off in late November.

They're also believed to be capable of feeding on brown marmorated stink bugs, a serious agricultural pest that local spiders tend to avoid.

"Joro spiders present us with excellent opportunities to suppress pests naturally, without chemicals," Nancy Hinkle, an entomologist at the University of Georgia, has said.

"I'm trying to convince people that having zillions of large spiders and their webs around is a good thing."

Joro spider eating a grasshopper
A joro spider feeds on a small grasshopper in a forest near Yokohama, Japan. The species is native to Japan, Korea, China and Taiwan, but has rapidly spread across Georgia. David Hansche/iStock