Joro spiders are here to stay
Q: We have been invaded by Joro spiders. I have not seen a single big yellow garden spider in my gardens where there were dozens last year. What can I do to kill off these unwanted pests?
A: There is not much that can be done. They are here, they compete strongly with other spiders and there’s no effective way to control them in the wide area where they are now entrenched. I saw my first one in October, 2021 and have seen many more in my north Decatur neighborhood since.
Female Joro spiders are big (perhaps 3″ across), similar to the common garden “writing spider” which most folks recognize. The difference between the two is that mature female Joro spiders have distinctive yellow stripes on their backs and bright red markings on their undersides.
Their webs are enormous and appear to be golden in late afternoon sunlight.
Joro spiders have spread widely since a gardener in Hoschton found the first one in 2014. They probably arrived in a shipping container from China or Japan. Females mature in early September and die by late November, along with the much smaller males. The spiders have now been spotted in at least twenty-three Georgia counties, as far west as Alpharetta and north to Rabun and Union counties. So far, they have been reported nowhere else in North America.
I think that unless a natural predator steps up to the plate there’s no way the Joro invaders can be controlled. There are just too many of them. But I remember that in 2009 we had the same worries about the kudzu bugs moving into the peanut and soybean fields and decimating both crops. Fortunately, a tiny parasitic wasp and a natural soil fungus teamed up to wipe out that huge population of invaders.
Also see Destroying a Joro spider egg sac