Creating a wildlife haven one plant at a time

Sunday, October 1, 2017

New Find: Joro Spider

Late this summer we discovered a spider that we had never seen before. As is always the case when we find a 'new to us' creature in our garden we dive into research mode and try to figure out what we have. This time we came up empty.


I reached out to one of my favorite ID sites, Bug Guide, to assist in identifying this spider. They did not disappoint. In a few hours we had our answer. We have a Nephila clavata, also known as the Joro spider.  According to Japanese Mythology, this spider is a deceptive shape-shifter (you can read the story at Yoki.com) but I prefer the Korean translation, which means Asian 'Fortune-Teller'.


This is a golden orb weaver that is similar in size to our common black and yellow garden spider (Argiope aurantia); however, the Joro spider is native to East Asia (Japan, China, Korea and Taiwan). How did this lady find her way to our garden? More research was required to unearth her story.

Left: Argiope aurantia (female),    Right: Nephila clavata (female)

According to a 2014 study (*) by Georgia Museum of Natural History at UGA, several Joro specimens were collected in three Northeast Georgia counties (Barrow, Madison and Jackson). These were the first confirmed Nephila clavata in North America and scientists think they arrived as stowaways on cargo ships. Obviously, we are not close to a port but we are located along I-85, a major commercial transportation corridor. It is believed that shipments traveling through our area contained egg sacs, which hatched spiderlings upon arrival. The study sited Braselton Park (in Braselton, GA) as one of the collection locations, where they found a female spider with two male spiders attending her web. This park is about 10 miles away from us and located near a thriving warehouse and distribution district, which deals with overseas freight.




The Joro spider is pretty spectacular looking. The top of the female's abdomen has a wavy black and yellow pattern while the underside is an amazing black and yellow maze with distinct red blotches. The black and yellow striped legs are also prominent. Our spider has gotten rather large over the past two months, approximately 4" wide [including its leg span]. 

top view of abdomen with grayish-black and yellow stripes.

The web of this spider is impressive too. She's set up at our woodland edge between two understory trees and large shrubs spanning a space of at least 5 feet. The web is built in three layers, uncharacteristic of orb spiders. The multilayered structure includes a large orb in the center with an additional front and back layer with irregular threads. The photo below doesn't do it justice, but the golden silk glistens when the morning sun hits the web.


Our spider's web is filled with insects, leaves, and other debris so fortunately it is hard to miss. We definitely wouldn't want to mistakenly walk into this sticky web. When prey is caught in the web the Joro spider immediately bites her victim inserting a potent venom. [Note: The venom is not strong enough to harm a human unless one has an allergic reaction. If bit by a Joro spider, humans typically experience pain, redness and blistering that disappears within 24 hours.]

Male spiders lurk in the outskirts of the web and are significantly smaller and and light brown in color. I have searched assiduously but have been unable to locate a male. Mating season occurs in October, which produces a single egg sac containing 400-500 eggs. The silk cocoon is attached to the bark of trees, on leaves or other human structures. Adults die in the winter leaving the next generation to hatch in spring.

This Asian spider has a North American relative, Nephila clavipes or golden silk spider, which is common in the southeast. The impact this exotic spider will have on our local ecosystem is unknown at this point. Interestingly, there are about 60 species of non-native spiders, mostly originating from Europe and Asia, thriving in North America thanks to international trade. According to Hoebek "there is no indication that the Joro spider will be invasive to the extent that it would be disruptive or economically costly". I wonder how this spider will interact with our native spiders. Will it displace any of our garden spiders or other native spiders? 


It is probable that the Joro spider has established itself in other areas of Georgia and across the country. Apparently this spider can withstand pretty cold temperatures (so be on the lookout northern friends). If you suspect you've discovered a Joro spider contact Hoebeke at rhoebeke@uga.ed. The initial discovery of this spider in our area was because of local residence, which demonstrates just how important citizen scientists are.

(*) study cited Hoebeke ER, Huffmaster W, Freeman BJ. (2015) Nephila clavata L Koch, the Joro Spider of East Asia, newly recorded from North America (Araneae: Nephilidae) PeerJ 3:e763

14 comments:

  1. Wow, I have not seen this one before...will keep an eye out for it. This time of year I am always walking into webs.

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    1. Yes! There are so many spider webs around the house and garden. I love observing them, they are so fascinating but it definitely isn't fun to walk into a web.

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  2. I haven't seen this one here in Nashville, but will be paying attention.

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    1. Yes, do. I am hearing from area residence that once this spider appeared in their garden, our native writing spiders disappeared. I wonder if is any further research is being done on their impact.

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  3. Look at those legs and 4" long! There are some cold areas in Japan, so I'm wondering how far north this species will venture.

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    1. It is a big, fat spider, but with it's large web difficult to miss. Plus the webs are pretty high off the ground. Only time will tell how far these spiders will travel. Down side of international commerce.

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  4. I'm pretty sure that this is the spider that has completely displaced the writing spider that used to live on my property. Thanks for the link. I've been concerned about it but haven't seen much from anyone else who seems to be. I'm in the Southern Piedmont of NC.

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    1. Thanks for commenting. I'm surprised it's made it to your neck of the woods already. I am hearing similar stories of the writing spider disappearing from gardens once this Asian spider established itself. If I find anymore information I will update this post.

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  5. She is a beauty! Yeah, I'm not familiar with this one, but it sounds like it's starting its N.A. infiltration in the south. Hopefully, it won't be a problem--invasive or disruptive.

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    1. Beth, I'm hearing from several local friends that they have lots of these spiders in their garden. It seems to be establishing itself pretty well in a short period of time. That never seems like a good sign to me. Anecdotal stories say that once this Asian spider appears, our native black and yellow spider disappears. Don't know if the Asian spider is outcompeting or just coincidence.

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  6. A very cool spider. Worth appreciating - from a distance! Great pics.

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    1. We've been watching her for about a month now. She is fascinating and we are learning a lot.

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  7. Wow, that is one impressive looking spider! One does wonder though about the native ecosystem with these different insects finding their way over here...

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