Two years ago and new to Georgia, I saw my first Joro spider along the Yellow River. Trichonephilia clavate is a beautiful spider, with gold bands at the joints of blue-black legs. It’s also from Asia. It’s an invasive species first seen in this region in 2014.
In the past two years, I’ve seen more Joros. On Sept. 25, I posted a note about finding a mantis, a fearsome predator, trapped in a web. I’ve been wondering what Joros have been doing to the native wildlife. I’ve been wondering particularly about the native spiders, the orbweavers.
Robert W. Pemberton of Atlanta published a paper that answered that question.
Using a technique called a Pollard Walk, he surveyed spider populations in 25 forests around Atlanta for three years: 2022-24.
The basic idea of a Pollard Walk is to imagine that you are in a 5-meter box. You walk along a set course on a schedule and record the species of interest you see in your box.
Pemberton found that the number of Joro spiders increased 50 percent a year. The number of orbweavers declined 40 percent a year.
Pemberton’s paper is so simple and elegant, it’s a thing of beauty to me. But it’s disturbing. What is the ethical thing for a householder to do? Let nature take its course or intervene on the side of the natives?
• Source and notes: Robert W. Pemberton, “Explosive Growth of the Jorō Spider (Trichonephila clavata (L. Koch): Araneae: Araneidae) and Concurrent Decline of Native Orbweaving Spiders in Atlanta, Georgia Forests at the Forefront of the Jorō Spider’s Invasive Spread”; Insects. 2025 Apr 23;16(5):443. doi: 10.3390/insects16050443. It’s here:
https://pmc.ncbi.nlm.nih.gov/articles/PMC12112690/
For my first encounter with a Joro spider in Georgia, see “A spider that poets loved,” Oct. 9, 2023.
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