Athens News Matters: The Joro Spider - Should we be Worried About Their Surging Numbers?
If you live in northeast Georgia, you’ve probably seen a Joro spider. More likely, you’ve probably seen dozens of them recently. They’re big, brightly colored and lately, they seem to be everywhere.
Elliott: “Once you start looking, they’re all over. I’ve had probably two-hundred in our yard, which is a third of an acre.”
That’s Matt Elliott, Assistant Chief of the Wildlife Resources Division of the Georgia Department of Natural Resources.
Elliott: “You know, I’ve noticed them in the past, but this year seems to be the year that their population has really exploded.”
You know, I've noticed them in the past, but this year seems to be the year that their population has really exploded.
Native to East Asia, Joro spiders were first discovered in Georgia in 2014. And they’ve been spreading and expanding in population ever since—reaching at least 25 counties in northeast Georgia, according to the University of Georgia’s Center for Invasive Species and Ecosystem Health. This has some ecologists, like Elliott, concerned about the Joro’s impact on the area’s ecosystem.
Elliott: “I think basic ecology of invasive species will tell you that especially a predator like that that increases in such vast numbers in such a short period of time is probably having some effect on the ecosystem”
But some entomologists, like Nancy Hinkle, Professor of Entomology at the University of Georgia, welcome the new species.
Hinkle: “I think we should look at them as good creatures serving a useful purpose and allow them to do their thing for a few years, until we can see just what kind of impact they’re going to have on the ecosystem.”
I think we should look at them as good creatures serving a useful purpose
But more on that in just a moment. First, how do you know the spider in your yard is a Joro and not, say, a yellow garden spider?
Hinkle: “Yes, let’s know what creature we’re talking about. The Joro is a larger spider. And she’s usually quite noticeable…. She’s dramatically colored. She’s got a red spot on the end of her abdomen.”
Look for bright yellow backs with horizontal, blueish green bands and black legs with yellow bands. The males are brown and much smaller. And then there’s the spider’s web, perhaps the most memorable part of the Joro experience for anyone whose bumbled into one.
Hinkle: “If you get the light just right, it’s truly magnificent. They look like they’re spun of fine gold.”
But they’re also strong and sticky.
Elliott: “I described them as being somewhere between silly string and fishing line.”
Whether a Joro web is considered gorgeous or just gross is a point at which Elliott and Hinkle differ. They do agree on one thing, however; it catches nearly everything. For Hinkle, the web eliminates pests.
Hinkle: “So all those thrips, all those aphids, all those moths that are laying eggs in my garden and eating up my tomato plants. Anything that gets caught in the spider web no longer can reproduce, can no longer contribute to the population…. So, to me, that’s a good thing. It’s like a giant glue board. It’s removing pests from the atmosphere.”
Elliott contends that it isn’t just garden pests that get caught in the webs.
Elliott: “They’re a generalist predator. They’re eating the insect population at large. So, besides mosquitos and stinkbugs, there’s certainly a lot of other things that they’re eating. And there have never been spider predators in that kind of abundance, that I’ve ever seen around here.”
Hinkle says that those giant webs could be taking prey away from native spiders. And that’s a major concern for Elliott.
Elliott: “There’s a lot of anecdotal evidence that the yellow garden spiders or the writing spiders have declined as the Joros have increased in abundance…. There’s not any hard data on that yet, but there’s enough for me to think that’s probably true.”
And a simplified ecosystem is a less resilient ecosystem.
Elliott: “It’s a loss of our native biodiversity, it’s part of the character of the area… and you end up with a simplified ecosystem with less diversity.”
Hinkle agrees, but says more study is needed.
Hinkle: “They’re new to this area, so we don’t know that much about them. This will be something that graduate students will be working on in the future—answering questions like this. When do they lay their eggs? Do they overwinter as eggs? So many questions for which we don’t yet have answers.”
Nancy Hinkle and Matt Elliott both agree that there’s not a lot to be done about the Joro population, at least as a regional phenomenon. There are just too many of them. But Elliot says, in your own yard, there may be something you can do.
Elliott: “I’ve taken the approach of getting rid of them in my yard. And I have seen some, I think, hopefully, some response from some of the natives. You know, maybe we can keep a little bit of what we want around if we create that space for them.”
There’s still a lot of research to be done into Joros, as Nancy Hinkle notes, but it appears that the adults will be gone, at least temporarily, pretty soon. And until then, keep an eye on where you walk.