Palm-sized Joro spiders reach Southern California, but experts say not to fear them

A palm-sized spider with vivid coloring has turned up in Southern California, marking the latest expansion of the Joro spider in the U.S.

Although its appearance can be jarring, specialists say the species poses far less risk than its size and colors might suggest, as FOX26 reported.

What happened?

Native to eastern Asia, the Joro spider is making its way to Southern California. Adult females are especially conspicuous, with yellow-and-blue coloration that makes the species easy to spot, the station noted.

Ecosystem expert Rebecca Wallace said residents do not need to panic.

"They may look intimidating, but they're not something to be afraid of," Wallace told FOX26.

The spiders do have venom, as many spider species do, but specialists say it is not considered medically important for people. The station noted that a bite could still possibly cause an allergic reaction or infection. Researchers are still trying to understand how far the species is spreading.

They think people likely helped bring the species to the United States, possibly through cargo shipments or on vehicles, per FOX26. Wallace explained that from there, the spiders are expanding on their own.

"They can disperse through a process called 'ballooning' or 'kiting,'" she told the network. "Spiderlings release a silk thread that can catch the wind or attach to distant objects, allowing them to travel far from where they hatched."

Why does it matter?

Any new species appearing in a region can raise concerns, particularly when it has already established itself in multiple states. FOX26 said the spiders have been reported in Maryland, Pennsylvania, and Virginia.

While experts are not raising major alarms about human health, they are still working to understand what the spiders could mean for native insects and food webs over time.

Its presence in the country appears to be connected, at least partly, to the movement of goods and vehicles.

What can I do?

FOX26 noted that people who believe they have seen a Joro spider can photograph it and submit the sighting to JoroWatch.org, where researchers can assess the images and help verify what was found.

That kind of reporting can help scientists build a clearer picture of where the species has taken hold and how quickly it is spreading.

For now, it's unclear what effects the Joro spider is having on the ecosystem.

"We know they're established and self-sustaining," Wallace shared with the station. "But we don't yet know what impact they're having on native wildlife."

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