Photo: Jen Wolf (Shutterstock)
To read the headlines from the last few days, you would think the entire eastern seaboard is about to become the setting of a horror movie. “Giant” spiders “the size of a child’s hand” or “the size of an adult’s palm” are “expected to colonize the entire East Coast.” They’ll use “tiny, terrifying parachutes” to “drop from the sky.” Oh, and they’re venomous.
Go ahead, scream. Vow to never go outside again. Come back when you’re ready, and we’ll talk about what these spiders—they’re called joro spiders, by the way—are actually like.
Are joro spiders venomous?
Yes, but so venomous that they will hurt you.
Here’s the thing: All spiders are venomous. What we call venom is their way of digesting food. Remember, spiders eat bugs and creatures smaller than themselves, and the venom is what they use liquify and gulp down their prey’s insides. That’s pretty metal, but on a small scale. If you are larger than a housefly, you don’t have much to worry about.
Some spiders do produce enough venom to cause their bites to be painful (or, in rare cases, deadly) to humans. But the joro is not one of them. Its fangs aren’t usually even big enough to get through human skin. You’ll be fine.
Are joro spiders actually as big as your hand?
No. Some of those recent reports have gotten a bit carried away. Joro spiders are all legs, and if you include outstretched legs in your measurement, the adults measure about three inches wide.
Reports have compared the spider’s size to a child’s hand, or to an adult’s palm. Like, okay, but barely. These spiders are bigger than what you’re probably used to if you live in the northeast, but they’re not tarantula-sized or anything. Here’s a photo of a joro spider on a person’s hand. It’s about twice the size of its close relative the golden silk spider, also called the banana spider, which already lives in the southeastern U.S.
Are joro spiders going to rain from the sky?
This is another exaggeration. The truth is that these guys, like many other spiders, can travel by “ballooning.” This means they release a few strands of silk into the air and let the wind pick them up (this phenomenon was illustrated in the “adorable” ending of Charlotte’s Web). They can float for miles if they catch the right breeze, which has led to speculation that a few of them might be able to make it as far as D.C. this year.
We don’t actually know how far they’ll be able to travel, though, and there’s no reason to believe they’ll be dropping from the sky all over the east coast. The recent fuss was sparked by a study from researchers at the University of Georgia, where they calculated that the joro spider should be able to withstand cold temperatures.
Joro spiders, originally from Japan, have been living in Georgia since 2013. Now that we know they can survive cold temperatures, it’s reasonable to start looking for them in colder areas—hence the warnings that they might make it to the northeast. But they aren’t planning a mass migration.
Should you kill joro spiders?
No, actually! Some invasive species can be problematic in their new environment. Lanternflies, for example, have “squish on sight” status where I live in Pennsylvania.
But joro spiders aren’t expected to cause any significant damage or disruption. They’re just spiders, and they just want to eat bugs. They might actually be beneficial, since they can eat mosquitoes, stinkbugs, and other insects that are themselves problematic. One of the authors of the new study told the press that “people should try to learn to live with them,” and that there’s no need to kill a spider that’s just trying to live its little spider life. I, for one, welcome our new stinkbug-eating overlords.
