Joro spiders are making headlines, but the sensational stories being spun about them have put our non-native spiders in the crosshairs, while leaving the average person confused about whether the Joro poses any risk to their gardens and pets.
The articles aren’t being written by experts and the titles foment fear with terms like ‘invasion,’ ‘take-over,’ ‘massive’ and ‘venomous.’ I found many errors — as well as outright fear-mongering — in my review. And those errors stick around: A gardener friend asked if I’d heard about “those Japanese spiders, parachuting down from the sky by the thousands.” When I told him I had, he confided in me, “I hear their bite is deadly.”
This isn’t true, but it makes for an exciting news segment. Another friend came to me proclaiming to have finally identified the large spider in her front yard as an invasive species. It turned out to be a native golden silk orb weaver.
A Forsyth County man set his house on fire trying to eradicate the perceived threat after being alarmed by sensationalist media coverage. (1) Clearly there’s just a lot of bad information out there.
Here’s a rundown of the facts:
- The Joro (Trichonephila clavata) has already been in our area for at least 8 years, during which time they have settled in nicely side-by-side with our native species.
- There’s no bite risk to humans or mammals. Their fangs are too small and weak to effectively pierce human skin, but even if they were to succeed, their venom is mild and has evolved to harm insects, not mammals.
- While their babies do “balloon” as many spiders do, traveling in the breeze on strands of silk, adult Joros certainly do not parachute down in the thousands.
- Their prey includes pests such as the invasive crop-damaging brown-marmorated stink bugs (which many spiders won’t touch), mosquitos and yellow jackets, making the outdoors a little more pleasant for all of us and helping farmers naturally control pests.
The news stories routinely confuse two different things: Invasive species that come in and cause major problems (think fire ants), and non-native species that find a comfortable place in their new ecosystem, and do not cause harm. Joros are non-native, but are not considered to be invasive.
Worse, still, some news stories post pictures of the wrong spiders. They confuse the Joro with similar-looking native species like the golden silk orb weaver, Trichonephila clavipes, or with other native black and yellow species like the writing/garden spider, Argiope aurantia. The truth is, most of us would have trouble telling the difference between these spiders. IDs are best left to the experts.
Why is it difficult to ID the Joro? The Joro and the native golden silk orb weaver both spin webs that are gold in color. Both are large spiders that have very large webs that become noticeable in fall. Both are primarily yellow and black, with yellow and black striped legs and a yellow body with a red or burgundy spot on their underside, and a bright yellow mottled pattern on their back. But both species have variations in colors as well!
Is it really a Joro Spider?
Can you tell which of these are Trichonephila sp.? Can you tell which are non-native Joro spiders, Trichonephila clavata and which are the native golden silk orb weaver, Trichonephila clavipes? I’ve been talking with my spouse about the misinformation on Joro spiders for months now, and he still wasn’t able to identify the spiders in these photos with confidence. I’ll put the answers at the bottom of the article for anyone who wants to try their hand at identifying our native species versus the non-native Joro.
What do the experts say?
Will Hudson, a University of Georgia extension entomologist, explained, “People shouldn’t be frightened of the spider at all, and in the event they ever cross your path, admire them,” he said. “They are really cool, and they are beautiful. You can go over and admire it, you can get as close as you want to get a really good picture with your cell phone… They’re just spectacular.”
Hudson says he’s held them numerous times, and his grandchildren even hold them. “They’re completely harmless.”(4)
Nancy Hinkle, another UGA entomologist adds “Joro spiders present us with excellent opportunities to suppress pests naturally, without chemicals.” She is trying to convince people that “having large spiders and their webs around is a good thing.” (5)
Nancy Hinkle, UGA entomologist, handling a Joro spider. https://pbs.twimg.com/media/FA4XtgwX0AQNzDm.jpg
Entomologist Linda Raynor, who specializes in behavioral ecology and the evolution of sociality in spiders at Cornell University, says “There is no evidence that this spider presents any sort of an ecological risk or risk to people or pets of being bitten. The only way you get bitten by orb weavers is if you put your fingers in their faces, and even then, it is rare.” (6)
Richard Hoebeke was the first to positively identify a Joro spider in northern Georgia in 2014. This past year he said, “I think people need to make peace with Joros and accept the spiders because they are not going anywhere.” (5)
The Rule of Thumb
Here’s the moral of the story: If you see one of these spiders, take a moment to enjoy and marvel at the colors, the beautiful architecture of its web, the wonderful role this creature plays in keeping the balance of insects in check. Don’t like spiders? No problem! Leave them alone, and they’ll return the favor. No need to kill them.
(2) Joro Spiders: What You Need to Know – Alabama Cooperative Extension System
(3) Learn – Invasive & Non-Native Species (U.S. National Park Service)
(4)Scared of the palm-sized Joro spider? What to know about the ballooning, ‘beautiful spiders’
(5)Palm-sized, invasive spiders are spinning golden webs across Georgia in ‘extreme numbers’
(6)Nothing to fear as ‘stunningly beautiful’ Joro spider treks north | Cornell Chronicle
Photo ID:
1. Non-native Joro (Trichenophila clavata)
https://news.uga.edu/joro-spiders-likely-to-spread-beyond-georgia/
2. Native Writing spider (Argiope aurantia)
https://www.taringa.net/+imagenes/la-telarana-mas-curiosa-del-mundo_12vx71
3. Native Golden Silk Orb Weaver (Trichenophila clavipes)
https://www.facebook.com/groups/antmans.hill
4. Native Writing spider (Argiope aurantia)
https://bugguide.net/node/view/924138/bgimage
5. Native Golden Silk Orb Weaver (Trichenophila clavipes)
https://www.facebook.com/groups/antmans.hill
6. Non-native Joro (Trichenophila clavata)
https://www.facebook.com/groups/antmans.hill