Three-inch Asian orbweaver spider spotted for the first time in Santa Barbara County
SANTA BARBARA COUNTY, Calif. (KEYT) – A three-inch long Joro spider (Trichonephila clavata) was spotted at a local Santa Barbara County business this fall.
The potentially invasive species is harmless to humans, but this is the first time it has been spotted west of the Great Plains region shared the Santa Barbara Museum of Natural History Tuesday.
According to the Santa Barbara Museum of Natural History, the single female spider is believed to have hitched a ride on plants shipped from another part of the country and was found near where shipments of plants are received.
Collective nursery plants, such as cut flowers and potted plants, were the second-highest valued, non-cannabis crop in Santa Barbara County last year.
"Insects and arachnids—being very small and easy to overlook—are easily transported unintentionally," explained the Santa Barbara Museum of Natural History's Schlinger Chair of Entomology Dr. Alex Harman. "In addition to things like spiders that are on vegetation, there can be insects inside wood. It’s not uncommon for wood-boring insects to be transported inside wooden pallets, furniture, or firewood. Sometimes wood-boring beetle larvae can take over a decade to mature, so those insects can pop out in a new area long after the wood was moved."
Dr. Harman mentioned invasive beetles because while spiders may appear scarier, the impact by invasive beetles can be substantially more pronounced as spiders tend to be more generalist hunters while beetles, such as the Emerald Ash Borer, are more specialized in their prey selection.
"If you think of the Emerald Ash Borer, it feeds on ash trees," explained Dr. Harman. "You can measure that the ash trees are dying because of this beetle. But spiders are generalists, mostly eating small insects trapped in their web, and it’s a lot harder to measure an overall decline in their insect prey, or a decline in native spiders getting outcompeted by invasive spiders."
The distinctively yellow, grey, and black spider is an orbweaver native to east Asia that could potential compete with indigenous orbweavers.
Joro spiders have been observed creating webs as wide as ten feet and were first spotted in the United States near homes in Georgia in 2014.
Since then, they had been observed as far west as Oklahoma and as far north as Maryland, but now that range has extended into the local area.
"Just like specimens of all the other living organisms in museums, insect collections are a great source of data for seeing how ranges change over time," shared Dr.Harman. "It's important to establish baseline data of what insects are found where, and in what habitats, to see how their distributions shift over time."
That notable coloration and size is why local naturalist and birding instructor Sophie Cameron recognized the visitor as a female Joro spider explained the Santa Barbara Museum of Natural History.
Cameron notified Dr. Alex Harman who confirmed the identity, captured the spider, and preserved the specimen among hundreds of other insects and arachnids in the Museum's Entomology Collection.
The sighting was reported to scientific journal Southwestern Entomologist to help track sightings nationwide.
Cameron intends to keep a watch on the location she first spotted the spider to ensure there isn't a more established presence beyond the single female visitor.
If you spot a Joro Spider or just want more information, you can reach out to the Santa Barbara Museum of Natural History at 805-682-4711.
