This Invasive Spider Species Loves Cities. Here’s Why.

A large, multicolored orb arachnid, called the Joro spider, is causing a stir in the media thanks to its arrival and rapid spread across the United States (U.S.). Read on to find out where this spider came from, where in the U.S. it is found, and how it is adapting to city living.

Wild Animals in Cities

The spread of human settlements and the urbanization of previously rural landscapes is bad news for many animal species. Habitat loss is one of the main drivers behind many species becoming endangered. Other animals, however, have found ways to adapt to living near and alongside humans. Some have even found ways to exploit the new habitats created in urban locations. Walk around an average city and you will see wild birds, insects, and even mammals. You will also see spiders! Several arachnids live around human dwellings, and one new arrival in the United States, the Joro spider, is thriving in many big cities.

The Joro Spider

The Joro spider (Trichonephila clavata) is a native species of East Asia. It lives throughout China as well as in Japan, Taiwan, Korea, Myanmar, and parts of the Himalayas. Its name comes from the Jorogumo spider of Japanese folklore. It is a type of golden orb-weaver spider and spins its webs with a shiny golden silk. These webs are huge! They often span over 200 square inches and are typically suspended in trees or other tall structures. Female Joro spiders are also large, with a body length of around an inch, but the males are less than a quarter of that size. The females also have an easily recognizable color distribution. They have a bright yellow abdomen with five horizontal silver or bluish-green dorsal bands, pink to red ventral markings near the spinnerets, and black legs with yellow bands. The males are an unimpressive reddish brown, which probably explains why they are not spotted so often.  

Invasive Species in the U.S.

Joro spiders were first spotted in northern Georgia around 2013-2014 and have since expanded their range into neighboring states. However, its actual arrival likely predates these sightings, possibly by several years. Mature adults are usually spotted in late summer, but spiderlings are seen in early summer. As of 2024, the Joro spider was also found in South Carolina, North Carolina, and Tennessee, with additional reports in Alabama, Maryland, Oklahoma, and West Virginia, and has been reported as far north as New Jersey and New York. No one knows exactly how they arrived, but it was likely via international cargo shipments.

The spider has likely spread over this range by ballooning. Spiderlings do this by walking up to a high point and releasing a silk thread. Air currents and atmospheric electric fields are strong enough to lift them off the ground, as they are so tiny. Further spread due to human transportation cannot be ruled out.

Spider City Living

One of the reasons these spiders have spread so successfully is their ability to take advantage of human-made structures. They have been spotted building their webs on street lamps, telephone poles, and traffic signals next to busy roads. Here, they have to be able to tolerate the constant vibrations caused by heavy traffic.

A study by the University of Georgia published in 2024 found that Joro spiders are able to successfully build their webs on human-made structures near busy roads, tolerating urban vibrations and noise, and use these webs to catch prey. Busy highways usually present a lot of challenges for wildlife, including noise, air pollution, and vibrations. The road vibrations, however, do not stop the Joro spider from being able to detect prey in its web. However, the attack rates of the spiders living next to busy roads are slightly lower than elsewhere. As the spiders living near roads were not any smaller, researchers have suggested that they are targeting larger prey and therefore do not need to launch so many attacks.

Will the Joro Spider Spread Further?

Given its rapid spread in the U.S. and its ability to cope with busy, urban environments, experts expect the Joro spider will likely continue to expand its range. Thanks to its physiology and climate suitability, research suggests the Joro spider could potentially spread throughout most of eastern North America.

They feed on beetles, wasps, bees, butterflies, dragonflies, and other spiders. The impact this will have on other species is yet to be known. Humans have very little to fear from them. They may be large spiders (at least the females), but they are very timid and are not usually aggressive toward people. They can produce venom, and they will bite, but the quantity of venom is very small, just enough to subdue an insect. If you are unlucky enough to be bitten by one, it will feel like a bee sting. They are also not hard to miss given their huge, golden webs and brightly colored bodies!