Since they were first discovered in 2013, East Asian Joro spiders — which are native to China, Korea, Japan and Taiwan — have shown up in force in Northeast Georgia. In the eight years since that first siting, Joro spiders have been found in 23 Georgia counties and South Carolina. Named after the Jorōgumo, a legendary creature in Japanese folklore, the Joro spider is an invasive species to our area and has many homeowners apprehensive.
Although in the same genus as the writing and banana spider (Trichonephila), they should not be confused. Joro spiders stand apart by their larger size and distinctive, gold-tinted multi-layered webs. The brightly colored females have alternating yellow and black/blue segments and a splash of red on their abdomens. Including their leg span, these gals can reach up to 3 to 4 inches. The males are considerably smaller and are usually brownish in color. They mature in early September, mate and lay eggs and then typically die by late November. One female Joro spider can lay between 400-1,500 eggs in a year.
The Trichonephila genus of spiders are professionals at spreading. They use a ballooning technique, in which the spiders spin a web to catch the air current, allowing them to fly for up to 50-100 miles. Like all spiders, they’re venomous, with a bite comparable to a bee sting. However, unless a person is specifically allergic to Joro spiders, they shouldn’t be concerned. These yellow arachnids are not aggressive and will flee if their webs are harmed.
Although they are vulnerable to insecticides, pesticide use is not more effective than a stick and a shoe. Plus, by spraying insecticides, you could be harming native, beneficial insects. There are no known preventative measures to keep them away.
Madison County residents have spotted numerous of these large spiders with yellow markings along trails, in their backyards and on their porches. No one knows for certain how these intimidating arachnids made their way to Northeast Georgia, but they are certainly here and their numbers are rising.
Specialists at UGA have been investigating this species since its arrival in 2013, with a primary goal of understanding how they might impact the local ecosystem. It is too early to know whether the Joro spider will become the next invasive species that has a negative impact on our native wildlife, joining the likes of feral hogs, Asian clams, and kudzu. Biologists are concerned that the Joro spider will displace native spiders. Time will tell. A benefit of the new species is that they capture and feed on insects that local spiders do not – mainly the adult brown marmorated stink bug.
So, although they are quite a nuisance when running into their webs, Joro spiders do not pose an imminent threat. Once cooler temperatures arrive and those large females lay their eggs, we won’t see much of them until next year. But no doubt, Joro spiders are here to stay.