Joro Spiders Are Spreading—Here's What to Do If You Find One in Your Garden

If you're afraid of spiders, now is the time to stop reading. You won't want to know that the intimidatingly large Joro spider is becoming an increasingly invasive issue in the United States. If you live in the southeast, it could be just a matter of time before you see one.

While these vibrant yellow and black spiders look like something out of an arachnophobe's nightmare, that doesn't mean you should be afraid. "Joro spiders are larger in size than most species found in the U.S., giving them a threatening appearance," says Dr. Jim Fredericks, chief entomologist at the National Pest Management Association (NPMA). "But they are not considered dangerous to people or pets."

However, that's not enough to keep most people from recoiling when they see one, especially since the spiders have a reputation for flying, which is a terrifying but easy-to-explain process called ballooning. "Young Joro spiders or spiderlings release a small strand of silk, allowing them to move by catching onto an air current," says Fredericks, who assures the general public that adult Joro spiders do not travel this way.

Want to make sure you know what to do if and when you run into a Joro spider? Here's what the experts say about where they came from, how to spot one, and how you can get rid of them.

What Are Joro Spiders?

Joro spiders are native to East Asia, and they're believed to have hitchhiked their way to the U.S. via shipping containers (just be glad you never opened one in a package!).

They're Invasive With an Expanding Range

They first arrived in the southeastern United States around 2013, where they easily adapted to the climate. Joro spiders quickly spread throughout Georgia and South Carolina, but they've now been spotted as far west as Oklahoma and as far north as Maryland. Because they can withstand various climates, including freezing temperatures, it might be only a matter of time before they're in your state.

They Weave a Mighty Web

They are members of a family of spiders called orb-weaver spiders, which means, as you might assume from the name, they weave their fibrous silk webs in an orb shape. Each web is coated in a substance that traps prey. "These spiders, like your typical orb-weaver spider, eat various insects like mosquitoes, biting flies, and even stink bugs," says Scot Hodges, A.C.E. certified entomologist at Arrow Exterminators.

They Multiply Quickly

Hodges also points out that one of the biggest issues with Joro spiders is that they can rapidly multiply—which has expedited the invasive process. "They will leave behind egg sacs full of eggs (400 to 1500 versus 200 to 500 for native species). Once their eggs have hatched in the spring, the hatchlings will hitchhike and spread mostly by riding the wind on a single strand of silk, which increases the size of their habitat," says Hodges.

How to Identify a Joro Spider

You'll know you have a Joro spider on your hands when you spot one of two things: either their telltale golden webs or the spider itself, in all its massive glory. Fredericks explains that these spiders are typically dark blue-gray with brilliant yellow bands and red markings on their abdomens. It's the females that wear the peacock colors—males are primarily brown.

Female Joro spiders have a body size of roughly one inch and each leg can be up to four inches long. That means their total size can be nearly eight inches. "Male Joro spiders are much smaller, with a body size of approximately 0.25 inches," says Fredericks. While a male may fly under the radar, there's no mistaking a female Joro spider when you spot it. If you see their web first, expect it to be roughly three feet to nine feet with a golden cast.

What to Do If You See a Joro Spider in Your Garden

The first thing to do if you see a Joro spider in your garden is take a deep breath and calm down. "Though their large size and golden webs can be a nuisance and scary to unknowing individuals, there is no need to worry," says Hodges.

Leave Them Alone

Unless you have a Joro spider infestation that has encroached upon your home or it's causing a serious annoyance in your yard, just leave the spiders alone. They prey on insects that you definitely do not want in your yard, and, depending on your level of comfort near a spider, they can be incredible to watch.

Call an Exterminator

If the spiders are truly bothering you and your quality of life, there's no reason not to exterminate them. After all, they are invasive and, while we don't yet know of any major environmental impacts, that doesn't mean they don't exist.

The first step in getting rid of Joro spiders is clearing their webs. "Pest control technicians can use special dewebbing brushes to clear visible webs on the outside of your home, which will be the most effective way to keep them from accidentally getting inside," says Dr. Daniel Kiefer, PhD, an entomologist at American Pest.

Then it's time to bring in a more intense chemical approach. "The most effective insecticides for Joro spiders are those containing bifenthrin, deltamethrin, or lambda-cyhalothrin, which will quickly kill the spider and its eggs and prevent further infestations," says Hodges.