A large, brightly colored invasive species called the Joro spider is on the move in the United States. Populations have been growing in parts of the South and East Coast for years, and many researchers think it’s only a matter of time before they spread to much of the continental U.S. But spider experts say we shouldn’t be too worried about them.
“My sense is people like the weird and fantastic and potentially dangerous,” said David Nelsen, a professor of biology at Southern Adventist University who has studied the growing range of Joro spiders. “This is one of those things that sort of checks all the boxes for public hysteria.”
Scientists instead worry about the growing prevalence of invasive species that can do damage to our crops and trees — a problem made worse by global trade and climate change, which is making local environmental conditions more comfortable for pests that previously couldn’t survive frigid winters.
“I think this is one of those ‘canary in the coal mine’ type species where it’s showy, it’s getting a lot of attention,” said Hannah Burrack, professor and chair of the entomology department at Michigan State University. But the shy critter poses little risk to humans. Instead, Burrack said, introduced pests like fruit flies and tree borers can do more damage.
The Joro spider is one of a group of spiders called orb-weavers, named for their wheel-shaped webs. They’re native to East Asia, have bright yellow and black coloring and can grow as long as three inches when their legs are fully extended. They are currently early in their life cycle, and a trained eye can spot their softball-sized webs on a front porch or their gossamer threads of golden silk blanketing the grass. Adults are most commonly seen in August and September.
Scientists are still trying to figure out where the Joro spiders are headed. Their central population is primarily in Atlanta but expanding to the Carolinas and southeastern Tennessee. A satellite population has taken hold in Baltimore over the last two years. The young spiders can use their webs to harness the winds and electromagnetic currents of the Earth to travel relatively long distances.
Joro spiders will eat insects that land in their web, potentially competing with native spiders for food. While some hope they could help control invasive species like spotted lanternflies, experts say there’s little chance of them making a significant impact. Joro spiders are not dangerous to humans, with venom that is not medically relevant. However, the introduction of other invasive species like the emerald ash borer or spotted wing drosophila could pose a more significant threat to natural resources.
In conclusion, while the Joro spider may be fascinating and capture public attention, it is not a significant danger to humans. Instead, the real concern lies in the broader issue of invasive species and their potential impact on agriculture, ecosystems, and human health. The spread of these species highlights the need for continued research, monitoring, and conservation efforts to protect our environment from further ecological damage.