Joro Spiders in Georgia: How Bad is This Invasive Species?

Written by AZ Animals Staff
Published: November 18, 2021
Image Credit iStock.com/David Hansche
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Northern Georgia has seen an invasive species bombard their communities. The Joro spider, native to East Asia, is spinning its web across porches, power lines, gardens, and vegetable patches everywhere you look. Technically, outside of the webbing, the joro spiders in Georgia have yet to cause direct harm to these ecosystems. But they’ve grown to become major nuisances.

Analysts estimate there could be millions of the creatures at this time with the possibility of the populace growth and expansion to other parts of the country.

What’s Going on in Georgia?

The proliferation of the Joro spider has blown up social media and even driven people to isolate themselves in their homes. In metro Atlanta, residents are stumped and stunned. They’re inadvertently coming upon the golden webs of a Joro, especially along the Chattahoochee River.

Homeowners are finding the populace thriving in their gardens and trees or making a nice home in their basements and crawlspaces. One homeowner found his front porch suddenly overtaken by Joro webs at least a size going 10 feet deep. That same homeowner says he killed over 300 of the invasive species on his property. The previous year, he’d only dealt with a few dozen.

The infestation is already expanding. The creatures are moving into South Carolina and it’s expected the population will continue to spread south. The species seems to be ignoring the natural flows in spider communities. These are often linked to local conditions such as changes in rainfall.

There is a theory that the Joro spider’s thriving in Georgia due to its similar climate to the spider’s original Japanese environments.

Are Joro Spiders a Threat?

Joro spiders use their venom to paralyze their prey, but it isn’t large enough to harm larger animals.

iStock.com/Jef Wodniack

Outside of the idea of how easily an invasion of creepy crawlies might overwhelm a community, the invasive species is actually no risk to humans or pets. The spiders have the capacity to bite. But their bite is too small to even break the skin. The venom they use to paralyze their prey isn’t strong enough to harm larger animals. There is the possibility of an allergic reaction.

But as the populace grows, researchers have yet to agree on what impact these spiders will have on other species and the environment.

There are those leaning towards positivity. Entomologists point out how Joros feed on unwanted insects, suppressing the population of yellow jackets, biting flies, and mosquitos. The invasive species is also a natural predator of the marmorated brown stink bug, a significant threat to Georgia crops and homes.

Still, the scientific community agrees no assessment of the Joro spider’s impact should be accepted too quickly. They want more research. A team at Clemson University in South Carolina says it’s too early to ascertain if there are negative connotations to this non-native and invasive species on South Carolina’s ecosystems.

Meanwhile, Georgia’s residents have to deal with the size of the growing invasion. Naturalists and garden lovers want to know more about these arachnids, particularly how they’ll affect other native spiders, bees, and other pollinators. The Joro makes larger pollinators part of their diet but the Joro will need more food sources.

Joro spiders might compete with other orb weavers for food or operate like some spider species, letting native spiders feast on food caught in their webs. There are simply too many unknowns to gauge what may come next. The only thing they’re fairly in agreement about is the likelihood they will return in larger numbers in the coming years.

How This All Started

The University of Georgia says the first sightings of the invasive species in the state happened somewhere between 2013 and 2014. In 2015, genetic analysis confirmed the sightings while the Georgia Museum of Natural History tracked the spread.

Now, this invasive species is new. The Joro spider is native to Asia and was only discovered there a decade before they showed up in Georgia. There has been no documented reason for how these spiders — already overwhelming huge portions of East Asia — got to Georgia. The best guess is the invasive species hitch a ride to the United States via a shipping container. Somehow, they’ve even narrowed that down to a container dropped off in the Braselton area along I-85.

Since its first discovery, the community’s size has grown in extreme numbers, landing in over two dozen Georgia counties. Soon, the crawlers would end up sighted in South Carolina. The animals appear to lean toward riparian and urban areas, mostly around houses. They also like to locate deep in wooded areas.

Scientific communities are guesstimating Mother Nature could eventually balance things out, returning the fast-growing number of Joros to normal levels.

An Overview of the Joro Spider

Joro spiders spin three-dimensional webs rather than flat webs.

iStock.com/David Hansche

Not a threat to anything except its natural food, encountering the Joro spider is more a nuisance than anything. Unlike many spiders who spin flat webs, the invasive species create almost three-dimensional webs. Also, they are orb weavers, meaning their wheel-shaped webs are not grayish-white but shiny gold. The webs can be large and multi-layered. Walking into them happens all the time and people are saying they’re sticky and hard to remove.

Females drop sacs of anywhere between 400 and 1,500 eggs. Compare that to the average native species leaving 200 to 500 eggs and you can see how fast the population can grow. Once eggs hatch in the coming spring, the hatchlings hitchhike or ride the wind on a strand of silk, landing and expanding in new habitats.

The Joro male has a brown body. It’s the female who stands out with her bright blue, yellow and red markings that cover their measures. What’s truly distracting is that the Joros can measure, with their legs extended, a good three inches across. In contrast, the average house spider is no more than 5/16th of an inch in length.

Prey & Predators

One benefit most of the scientific community attributes to the Joro is the impact the spiders have on pests. They enjoy brown stink bugs. The native spider won’t eat them and the stink bug is a significant threat to local agriculture. Joro spiders also feast on mosquitoes and yellow jackets. Another nice thing that’s pointed out is the invasive species do not appear to be displacing native spiders.

When it comes to predators, the Joro spider is food for wasps and mud daubers.

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AZ Animals is a growing team of animals experts, researchers, farmers, conservationists, writers, editors, and -- of course -- pet owners who have come together to help you better understand the animal kingdom and how we interact.

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