The New Invasive Species on the Block

If you live on the US east coast, you may have noticed some new visitors in your backyard: Joro spiders, a large and colorful species of orb-weaver spider native to east Asia. These spiders have been spreading rapidly in Georgia and South Carolina, and researchers predict they could soon colonize much of the eastern seaboard.

Joro spiders are not venomous to humans, but they can be intimidating to some people because of their size and appearance. Females can measure up to three inches across when their legs are fully extended, and they have striking yellow, blue and red markings on their bodies. They also spin elaborate golden webs that can span several feet and catch the sunlight.

Joro spiders are invasive species, meaning they are not native to the US and may have negative impacts on the local ecosystems. They may compete with or prey on native spiders and insects, or alter the food web dynamics. They may also pose a threat to agriculture, as they can feed on beneficial pollinators or damage crops with their webs.

How Did These Spiders Get Here?

So how did these spiders get here, and what can we do about them? Here are some facts and tips to help you cope with these new arachnid neighbors.

– Joro spiders are believed to have arrived in the US via shipping containers from east Asia, possibly Japan or China. They were first identified in Georgia in 2014, but their population exploded in 2021 due to favorable weather conditions.

– Joro spiders are adapted to colder temperatures than their relatives, the golden silk spiders, which have been living in the US south-east for over a century. Joro spiders have higher metabolism and heart rate, and can survive brief freezes that kill off other orb-weavers. This means they can potentially expand their range northward along the east coast, where Japan has a similar climate and latitude.

– Joro spiders are not aggressive or dangerous to humans or pets, unless provoked or threatened. They may bite if handled roughly or trapped in clothing, but their venom is mild and only causes mild pain and swelling. They are not known to transmit any diseases or cause allergic reactions.

– Joro spiders are beneficial in some ways, as they help control pests like mosquitoes, biting flies and stink bugs. They also provide food for native predators like birds, wasps and mantises. Some people may even appreciate their aesthetic value, as they add color and beauty to the landscape.

– Joro spiders are best left alone if they are not causing any problems or interfering with your activities. They are not territorial and will not defend their webs from humans. If you encounter a Joro spider web in your way, you can gently move it aside or cut it down with scissors or a stick. Do not use pesticides or fire to kill them, as this may harm other wildlife and the environment.

– Joro spiders are unlikely to invade your home, as they prefer outdoor habitats with plenty of sunlight and vegetation. However, if you find one inside your house, you can capture it with a jar or a cup and release it outside. You can also prevent them from entering by sealing any cracks or gaps around doors, windows and vents, and by keeping screens in good condition.

– Joro spiders are here to stay, at least for now. There is no effective way to eradicate them completely, as they are too widespread and prolific. However, researchers are monitoring their population dynamics and impacts on native species and ecosystems, and may develop management strategies in the future.

Joro spiders are part of a global phenomenon of biological invasions, where species cross borders and continents due to human activities like trade, travel and climate change. While some invasions may have positive effects, others may have negative consequences for biodiversity, human health and economy. As citizens of a connected world, we need to be aware of these changes and adapt accordingly