This weekend I received texted photo of a spider, with the question: “Friend or Foe?” What she meant, of course, is whether the arachnid posed a danger to her. The picture she sent was that of a Joro spider (Trichonephila clavate). I told her it wasn’t dangerous, but in truth it requires a more complex answer.
Until recently, I could comfortably identify the big spiders around my house as either the garden or writing spider (Argiope aurantia) or the golden silk orb weaver (Trichonephila clavipes). When late-summer spider season hit and webs were being spun in every available tree and porch pillar, the usual suspects aren’t in attendance. Instead, the Joro spider, an Asian native, has set up shop all over Athens and throughout our woods in a neighboring county.
In the Fall of 2014, a fellow in Madison County, Georgia, sent photos of a strange spider to the Department of Entomology at the University of Georgia. This is the first record of the Joro spider in North America. They probably arrived, as so many invasives do, in packing material for goods shipped across the ocean. Since then, they have expanded their range across the Piedmont of Georgia and South Carolina. Given that the spiders lay egg sacks with hundreds of eggs (up to 1500!), it is easy to see how they overwhelm the other large orb weavers in the ecosystem.
My ecologically-aware friend was incensed. “…are we just meant to let them naturalize, or are we supposed to be coming up with ways to get rid of them?”
Good question. If one species takes over a niche from another species, that is cause for a naturalist’s concern. Unfortunately, unless the usurper causes some economic harm, you aren’t likely to have any of the Powers That Be care enough to devote resources to it. Not that there is likely to be a way to combat this species that doesn’t threaten all other spider species.
No, I think we will see the Joro continue to spread and naturalize. They will capture insects with as much efficiency as their predecessors, and their bites are just as harmless to humans. Whether the transition of arachnid power will impact the ecosystem beyond displacing some species remains to be seen.
Spiders in Georgia: Identify the spiders you find.