Last fall, a lone Joro spider found itself very far from home.

Naturalist and birding instructor Sophie Cameron spotted the 3-inch-long spider at a local hotel in foliage clinging to a building, marking the first time the species had been found in Santa Barbara County.  

The yellow-and-black spider, which originates from East Asia, is harmless to humans. Over the years, the species has spread to the eastern portion of the United States; it was discovered in Georgia in 2014, according to the North American Invasive Species Management Association.  

Before the spider was found in Santa Barbara County, the furthest west the species had been spotted in the United States was Oklahoma.

Alex Harman, the Santa Barbara Museum of Natural History‘s Schlinger chair of Entomology, was alerted to the spider’s presence by Cameron.

Cameron identified the spider by its yellow, black and grey coloring, which indicates the spider is female.

The Joro spider, also known as Trichonephila clavata, can grow up to 3 or 4 inches, but can make webs that can span between 9 and 10 feet across.

Harman isn’t sure exactly how the spider got to Santa Barbara, but he suspects that it hitched a ride on a flower shipment to the hotel.

(The museum declined to name the business where the spider was found, stating they don’t want it to be publicly blamed or shamed for possibly bringing it to the area.)

“These hotels are bringing in lots of fresh cut flowers for weddings and parties and things like that,” Harman said. “…We suspect that the spider probably came in on a shipment of flowers.”

Harman told Noozhawk that allowing the spider to spread throughout the state could impact the local ecosystem. In a new environment, invasive species can have a disproportionate effect if they outcompete local species.

For example, the emerald ash borer — an Asian beetle that was introduced in the early 2000s — led to the death of millions of ash trees across the eastern United States.

Harman explained that in its natural habitat, the beetle can only infect dead or dying trees. Trees in the beetle’s natural habitat are resistant because the two evolved alongside each other.

In the United States, the trees did not have that same resistance to the beetle, and the beetles devoured large numbers of trees.

“The big concern is that an invasive species… doesn’t have any predators or parasites that help limit its population,” Harman said.

Those species can “have an oversized impact on its prey species that don’t have any resistance or ways to avoid them,” he added.

Harman said it isn’t known exactly what effects the Joro spider could have on the local region due to a lack of studies.

Several federal and state agencies look for invasive pests, including the United States Customs and Border Protection, the U.S. Department of Agriculture, and the California Department of Food and Agriculture (CFDA).

The local agency looking for invasive species is the Pest Prevention Division, part of the Santa Barbara County Agricultural Commissioner’s Office.

Invasive species are not limited to insects and spiders.

“A pest could be an insect, could be a disease, could even be a weed. They’re all kind of known as pests or invasive species,” said Stephanie Stark, the county’s deputy agricultural commissioner.

The division inspects shipments to make sure nothing dangerous is leaving or coming into the county.

Stark said the main things the division looks for are insects or plant diseases.

Part of the process includes inspecting shipments from trucks and packages shipped through the postal service. Inspectors from the office will examine packages that contain or may contain plant material to inspect for insects or signs of disease.

If the staff suspect a package is compromised, they may send it back to the sender or destroy it. Some samples may be collected for a lab to test whether it’s a pest or not.

The division uses a rating system to indicate how serious a pest is. One example Stark gave was the spotted lanternfly, native to Asia, which is considered an A-rated pest due to how fast it spreads and the damage it has done to parts of the East Coast.

The most common A-rated pest found in 2026 has been the lesser snow scale, according to Stark. The most common C-rated pest is the Argentine ant.

Even though the division inspects imports from other countries, it also keeps an eye out for any pests native to different regions of the United States. Some of the riskier shipments for local growers are from Hawaii and Florida.

Stark said that the rating system does not cover spiders, so the Joro spider would not have been a targeted species. However, if staff had seen it, they would likely have collected it for testing and alerted other agencies of its capture.

“It’s not a plant pest or a threat to agriculture, but it is a surprise that it is in the landscape,” Stark said. “So, it’s something that we probably would have alerted CDFA about it.”

Stark said if the public finds a species they do not recognize, they can alert their local master gardener or contact the Agricultural Commissioner’s Office, which will review it for free.

Stark also reminded residents that a common way for pests to enter the environment is through online sellers such as NextDoor or eBay. She added that the safest way to buy plants is through a licensed nursery.

After Harman collected the spider, he and his staff returned to the site to see if they could find more. However, they did not locate any others and believe the spider made the trip alone.

The spider is now being kept in the museum’s collection in a bottle of alcohol. The museum may use the specimen for testing in the future and as a record of its presence in the county.

Despite the spider’s size, he said it is not dangerous to humans or their pets. The larger concern is the lack of information about how they may affect the ecosystem if they were to be introduced into the environment.

Harman encouraged anyone who sees a Joro spider to contact the county or let the museum know.

“We’re crossing our fingers that it was just this one individual,” Harman said. “Again, it’s a big, scary spider, but it’s not going to hurt anyone. So, they don’t need to be terribly worried about it.”