You’ve likely seen the media headlines in recent years on Jorō spiders, calling them giant flying venomous spiders from Asia. While this is partially true (they are large, and they are native to Asia), many headlines exaggerate their threat and capabilities. Jorō spiders were first found near Athens, GA, in 2014 and are now becoming more common in GA, SC, TN, and NC. While it is unknown exactly how Jorō spiders arrived, they were likely inadvertently introduced to the area several years before their discovery, and they are spreading throughout the eastern U.S.
For up-to-date observations, see the iNaturalist Joro Spider Observations Map.
Jorō Spider Life Cycle
Jorō spider eggs hatch in late April to early May, and the tiny spiderlings are difficult to identify at this stage. Some spiderlings exhibit a behavior called “ballooning,” where they crawl to a high place and release some long silk strands. Air currents bring the silken draglines aloft, carrying the spiderlings over potentially long distances. This is the only life stage when the Jorō spiders ever travel through the air, and it is a common behavior among many species of spiders. Spiderlings choose a spot, make a web, and grow throughout the summer. Jorō spiders are typically not noticed until late summer, when they start to get larger and reach maturity.
There is strong sexual dimorphism (meaning males and females appear very different) in the Jorō spiders. The females are very large (their bodies can be over 1 inch long, and with their legs outstretched, they may have a span of 3 or more inches) and brightly colored, with silver stripes on their yellow abdomen. The males are much smaller (their combined body and legspan only reaching about 1 inch) and appear in various shades of yellow and brown. Once mature, males abandon web-making in lieu of finding a female’s web. Males often aggregate on the webs of subadult females, attempting to mate with them shortly after they reach maturity and then guarding females from the mating advances of other males. In late November and into December, females lay their eggs typically before the first major freeze. The adult spiders die in the winter, after the first freeze, and the next generation emerges in the spring. Estimates for the number of eggs within an egg sac range from 400-500 eggs, though the spiderlings will likely eat some of the other eggs and spiderlings within their egg sac.
A smaller brown male Jorō spider (upper left) next to a large mature female. Photo by iNaturalist user Ashley Bradford, licensed under the Creative Commons Attribution-Noncommercial 4.0 International Deed: https://www.inaturalist.org/observations/187864177.
A Jorō spider egg sac laid in captivity. Note the loose webbing that binds the egg mass to the substrate (in this case, a plastic lid). The eggs, which range from pink to brown in color, have been glued into an oval-shaped mass that is firm to the touch.
Angela Chuang, ©2024 Clemson Extension
Juvenile Jorō spiders often resemble other native orbweavers found in eastern North America and may escape notice until they are larger. Their abdomen has shades of white, black, and yellow patterning that changes as they develop.
Beth Biggs, ©2024 Clemson Extension
The Web
Jorō spiders are large spiders and make correspondingly big webs. Like its close relative, the golden silk orbweaver, Jorō spider silk is also yellow. The webs of these species are often built between large, sturdy physical supports at or higher than eye level. Jorō spider webs tend to be found at the edges of forests, in parks, on roadside vegetation, as well as in yards with trees. They can also be found on buildings and manmade structures, such as streetlights. The webs can vary greatly in size – while the central orb portion is typically around 2’ or so in diameter, the structural webbing can stretch several feet on each side.
Will a Jorō spider bite me, and is it dangerous?
Though the females are large and are capable of biting, they are very docile creatures – in fact, these spiders are much more likely to run away and hide than they are to bite. The authors have handled hundreds of Jorō spiders and have never been bitten from touching their webs, touching the spiders, or holding them loosely. Like with other spiders, a Jorō spider is most likely to bite a person if they are holding it tightly, such as gripping the abdomen tightly or holding the spider by its legs. Even in the latter scenario, Jorō spiders often break off their trapped legs to escape rather than bite their captor. People bitten may develop a small, red, itchy welt similar to a mosquito bite or bee sting, which usually fades within a day or two. Jorō spiders do have venom (all spiders have venom, as it is how they kill their prey), but it is not medically relevant and is not known to harm people or pets.
These three photos show an example of a reaction to a Jorō spider bite on the hand. Image A (to the far left) is immediately after the bite. Image B (in the middle) is five minutes afterward with visible swelling. Image C (to the far right) is twenty-four hours later, with faint red marks at the puncture sites.
Photos by Dennis Lieu, Southern Adventist University.
Have I found a Jorō spider or something else?
There are several large yellow orbweaver spiders in South Carolina, including the yellow garden spider, the banded garden spider, the golden silk orbweaver, and the Jorō spider. Please see HGIC 2513, Big Yellow Spiders fact sheet to learn how to tell these species apart.
How do I manage Jorō spiders on my property?
Jorō spiders are highly unlikely to come inside your home, but they may make a web on your house or other structures on your property. These spiders can be eliminated using any registered acaricide, or you can use a stick or broom to knock the spiders from their webs and physically eradicate them. They can also be moved far away from where they were (e.g., from your porch to the edge of the woods), as this is likely to keep them from returning to that location.
