Joro spiders and writing spiders are both large, colorful orb-weavers that show up in yards and gardens in late summer, and they’re easy to confuse at a glance. But they differ in important ways: their size, web structure, coloring, and origin. The Joro spider is an invasive species from East Asia that arrived in Georgia around 2013, while the writing spider (also called the black and yellow garden spider) is native to North America and found across the entire United States.
How to Tell Them Apart by Color
Both spiders have yellow and black markings, which is the main reason people mix them up. But the patterns are distinct once you know what to look for. Joro spider females have bright yellow, blue, and red banding on their legs, with a yellow-and-dark-blue striped abdomen. The overall impression is more colorful and complex, almost tropical-looking. Writing spiders, by contrast, have a cleaner black-and-yellow pattern on the abdomen, with solid black legs that have no colored banding. Their body shape is also rounder and more compact compared to the Joro’s longer, leggier frame.
Size and Web Differences
This is where the two spiders diverge dramatically. Mature female Joro spiders spin webs that can span 10 feet or more, using strong, sticky golden-yellow silk that’s among the strongest spider silk in existence. The support strands alone can measure up to 20 feet, stretching between treetops, poles, and shrubs. Joro webs are also typically built higher off the ground than most other orb-weaver webs.
Writing spider webs are much smaller, reaching about 2 feet in diameter. They’re built closer to the ground, often among garden plants and shrubs. The most recognizable feature of a writing spider’s web is the stabilimentum, a thick zigzag pattern of white silk running vertically through the center. This is the “writing” that gives the spider its common name. Adult Joro spiders never build stabilimenta in their webs, though their young spiderlings occasionally do. If you see a large web with a bold zigzag down the middle, you’re looking at a writing spider’s work.
Where Each Spider Lives
Writing spiders are native and widespread across the continental United States, including northern states like Pennsylvania. They’ve been a fixture in American gardens for as long as anyone can remember.
Joro spiders have a much more limited and rapidly changing range. First detected in northern Georgia, they’ve since spread into adjacent areas of Alabama, North Carolina, South Carolina, and Tennessee. An established population has also been found near Elkridge, Maryland. Between 2014 and 2026, Joro spiders expanded outward from their initial location by 50 to 80 miles, roughly 10 miles per year. Their young can also travel much farther through ballooning, a behavior where spiderlings release silk threads and ride wind currents tens to hundreds of miles. A single well-timed storm could push them into new territory in a large jump.
One reason the Joro spider’s range is expected to keep growing is its cold tolerance. In its native Japan, it lives in areas where average January temperatures drop to 25 to 32°F, comparable to much of the mid-Atlantic and even parts of the Northeast. Research confirms that Joro spiders have a shorter lifecycle and can survive colder temperatures than related species already established in the Southeast.
Are Either of Them Dangerous?
Neither spider poses a meaningful threat to people or pets. Both are orb-weavers, a group known for being non-aggressive. They sit in their webs waiting for flying insects, not hunting on the ground or seeking out contact with humans. Their fangs can technically pierce skin if you grabbed one, but the venom of both species is mild and not medically significant. A bite, on the rare occasion it happens, would feel similar to a mild bee sting at worst.
Do Joro Spiders Threaten Writing Spiders?
This is the big open question, and scientists are honest about not having a definitive answer yet. Both species eat flying insects, and both build webs in overlapping habitat types like gardens, forest edges, and suburban landscapes. The concern is that Joro spiders, with their enormous webs positioned high in the canopy, could outcompete native web-builders like writing spiders for prey.
A newly formed research team at the University of Georgia is actively studying whether Joro spiders displace native species. Spiders as a group are important predators, consuming an estimated 400 to 800 million tons of insects globally each year. Any shift in which species dominate that role could ripple through local ecosystems. For now, though, writing spiders remain common throughout their range, and there’s no confirmed evidence that Joro spiders are reducing their numbers.
Quick Identification Checklist
- Leg color: Joro spiders have yellow, blue, and red bands on their legs. Writing spiders have solid black legs.
- Web size: Joro webs span up to 10 feet or more. Writing spider webs reach about 2 feet.
- Web height: Joro webs are built high, often between treetops. Writing spider webs sit low, among garden plants.
- Zigzag in the web: Writing spiders build a prominent zigzag stabilimentum. Adult Joro spiders do not.
- Silk color: Joro silk has a golden-yellow tint. Writing spider silk is mostly clear or white.
- Range: Writing spiders live across the entire U.S. Joro spiders are currently concentrated in the Southeast, with an outlier population in Maryland.