They’re Huge, They’re Creepy, and They’re Back—An Expert’s Tips for Joro Spider Season

For residents of the southeastern United States, fall signals back Zorro spiders—huge, bright yellow arachnids native to Asia—are big enough to litter porches, gardens, and cast huge webs.

Zorros generally do not pose a serious threat to humans. But their autumn abundance appears to be a source of significant annoyance to local residents—something that David CoyleAn entomologist at Clemson University knows better than most, as South Carolina’s state adviser on invasive species.

After years of fielding Zorro-related complaints, Coyle and his team decided to formally investigate the findings — the result of a year-long effort to address the most common questions about the Zorro spider, the results of two studies, released Wednesday, Oct. 22. Journal of Medical Entomology And Journal of Economic Entomology.

Gizmodo spoke with Quail about spiders and shared tips for dealing with unwanted Zorro encounters. The following conversation has been lightly edited for grammar and clarity.

Geyoung Lee, Gizmodo: What are Zoro spiders and why are they considered aggressive?

David Coyle: Zorro spiders are native to China and parts of Asia. They first probably arrived in the US around 2010 but were first discovered in North Georgia in 2014. Since then, they have spread to multiple states, even to the Northeast. There are populations around Baltimore, Boston, and Pennsylvania. The hotspots are of course northern Georgia, western South Carolina and North Carolina, and far eastern Tennessee.

They’re an invasive species because… well, they’re not native to this continent, and they show pretty significant displacement of native species. This is the fifth year of our “spider surveys”, as we call them

And, where you have a large population of zorro spiders, you don’t have that type of native or weaving spider. It is still too early to know what their actual impact will be, but we are trying to track it.

Gizmodo: Why do people consider zoros pests?

Quail: They are incredibly pestiferous, as they are very comfortable living around human structures and landscapes. They won’t go indoors at all, but they will be in your bushes, carports, on decks, and across doors. They are also very large and yellow, so people notice them and we get a lot of calls about these things every fall

Gizmodo: What kind of call?

Quail: Broadly speaking, “How can I get rid of them?” Be it “out on my favorite bush” or “let them put a net across the pillars of my house.” The second most common question is, “Are they dangerous? Will they bite me? Will they bite my kids? Will they bite our pets?”

Because these webs are huge—they can be 10, 15, or 20 feet across—and you walk into them to find a giant spider on your head. When grown women, these big yellow and gray striped women, show up all over the place, people think, “Holy crap, what’s going on there?”

Gizmodo: And callers advice?

Quail: This is why we conducted new research. We wanted concrete answers that weren’t just anecdotal. Based on our team’s growing years of experience, we knew what happened here. To prove it we needed to do it in a scientific way.

Gizmodo: I see And how did you answer these questions in the paper?

Quail: I will start with what I call management studies Journal of Economic Entomology. “How can I get rid of them?” This was in response to the question. So we looked online because we thought this is where people go to find solutions.

We knew there were legitimate spider control products out there, so we tested several of them. Then we also evaluated things that we just found online: bleach, machine lubricant, hairspray, and some of those non-paste products that people use.

In a scientifically valid and systematic way, we tested each of these compounds on clusters of spiders to see if it would kill them, and if so, how long. If not, at least the spider will go? Because for some people, maybe they want it off their porch – not necessarily dead.

What we’ve found is that most commercial products work great. I’m not going to list any specific brands, but if it’s labeled as a spider control, those things work pretty well.

Other things worked too. I mean, machine lubricant works, but we don’t advocate spraying that stuff all over your yard. That’s not what it’s for. We strongly recommend using only those labeled for that purpose, as it works just as well

Gizmodo: d Second paper About whether Zoros is dangerous, right?

Quail: Right. We did a series of experiments where we watched a spider react to, essentially, a human hand. We walk up to the spider in the web. We did everything from just holding our hands to it, trying to touch it, holding it in our hands, cupping it in, squeezing it a little.

And in almost every case, that spider just wants to go away. They don’t want to be stuck. They don’t want to be touched. If you cup them in your hands, they’ll just sit there and freeze. The only time you can really bite them is when you can pinch them—as in, making it worse.

Then we said, “Okay, let’s say that somebody beats. How bad is that?” We got 22 volunteers and they were bitten by Zoros. We then tracked the bites for a week and rated the volunteers’ pain levels based on a system used by pediatricians.

What we found was that it resembled a mosquito bite. So it will be a little swollen, red and itchy for about 24 hours, then it’s almost gone. And most pain levels were very low, like 1 to 2 out of 10.

So the take home message is that if you’re going to get bitten by Zoro the Spider, you really need to be the Spider’s opponent.

Gizmodo: You probably brought this on yourself.

Quail: you 100% Bring it on yourself. As such, they want no part of you. They would rather not be on you. They would rather not be held by you. They just want to do their job and be left alone.

And if you accidentally walk into them, what is their reaction? They will drop to the ground and try to get away from you and get off of it.

Gizmodo: Having said all that, do you have any personal advice for co-existing with Zorro spiders?

Quail: You don’t have to use chemicals to get rid of these things. A broom works great, your feet work great, and a stick works great. And if you just knock them off their web a few days in a row, they’ll leave and go somewhere else. I always tell people that using chemicals for something like this is often overkill, figuratively speaking.

Then the other thing is that I would insist that they don’t come to your house. They don’t want to live in your house. This type of spider usually places its web between large outdoor objects so that objects can fly into it. So, if you have a Zoro spider in your house, it means someone brought it there. It’s plain and simple.