Meet the Joro Spider: Big, Colorful, but Not a Threat

A large, brightly colored spider called the Joro spider is making its way across the United States. This invasive species has been growing in numbers across parts of the South and East Coast for years. Many scientists believe it’s only a matter of time before these spiders spread to much of the continental U.S. However, experts say there’s no need to panic.

Understanding the Hype

David Nelsen, a biology professor at Southern Adventist University, studies the spread of Joro spiders. He believes the public's fascination with these spiders stems from their striking appearance and the fear of the unknown. “People are drawn to the strange and potentially dangerous,” he says. “This spider ticks all the boxes for creating public hysteria.”

But according to scientists, the real concern should be about other invasive species that can harm crops and trees. The rise in global trade and climate change allows pests that couldn't survive cold winters in the past to thrive now. Hannah Burrack, a professor and chair of the entomology department at Michigan State University, sees the Joro spider as a “canary in the coal mine” – an attention-grabbing sign that highlights a much larger issue. She stresses that pests like fruit flies and tree borers pose a far greater threat.

What is the Joro Spider?

The Joro spider belongs to a group of spiders known as orb-weavers, famous for their wheel-shaped webs. Native to East Asia, these spiders are notable for their bright yellow and black coloring. They can grow as long as three inches (8 cm) when their legs are fully extended.

Currently, these spiders are small, about the size of a grain of rice, as they are in the early stages of their life cycle. Their webs, which can be as large as a softball, can sometimes be spotted on porches or among the grass. The adult Joro spiders are most visible in August and September.

Where are They Headed?

David Coyle, an assistant professor at Clemson University, has been studying the Joro spider’s range. The central population is primarily in Atlanta, expanding to the Carolinas and southeastern Tennessee. There's even a satellite population in Baltimore. As for when they'll become more common in the Northeast, it's uncertain. “Maybe this year, maybe a decade,” Coyle says. “They won't spread that far in a single year; it will be a gradual process.”

Can They Fly?

Young Joro spiders have a fascinating ability to travel long distances using a method called "ballooning." They use their webs to catch the wind and electromagnetic currents of the Earth to float away. However, you won't see adult Joro spiders flying through the air.

What Do They Eat?

Joro spiders aren’t picky eaters. They consume whatever insects get caught in their webs. This means they might compete with native spiders for food. However, this could have a silver lining as well. Their daily catch could become a food source for native birds. Andy Davis, a research scientist at the University of Georgia, has observed this behavior firsthand.

Some people hope that Joro spiders might help control the invasive spotted lanternfly population, which is damaging trees on the East Coast. Unfortunately, they might eat a few, but it's unlikely they’ll make a significant impact on the lanternfly population, according to Coyle.

Are They Dangerous to Humans?

Like all spiders, Joro spiders have venom, but they are not dangerous to humans. The venom is not medically significant. At worst, a bite from a Joro spider might cause an itch or an allergic reaction. Generally, these spiders prefer to stay out of humans' way.

The Bigger Picture

The real threat to humans comes from other invasive species like the emerald ash borer or the spotted wing drosophila, a type of fruit fly. These pests threaten vital natural resources.

Andy Davis reflects on the broader implications, saying, “I try to stay objective, but it’s clear there’s a lot of ecological damage happening globally, largely due to human activities. The Joro spider is just another example of our impact on the environment.”

In conclusion, while the Joro spider might look intimidating, it poses little risk to humans. The attention it garners should remind us of the larger, more harmful issue of invasive species and the importance of managing our environmental impact.