ABOVE THE WATER LINE BY SALLY BETHEA
Because he spends so much time outdoors in nature for work and pleasure, photographer Alan Cressler rarely comes upon something that shocks him. Yet, that is exactly what happened in early October, when Alan spotted “literally thousands of golden webs with large, female spiders,” draping powerlines near the Chattahoochee River in north Fulton County. The early morning sunlight perfectly illuminated a massive procession of Joro spiders (Trichonephila clavata): the non-native, invasive species that is currently all the buzz on mainstream and social media outlets. Seven years ago, these strikingly colorful Asian spiders that “look like Halloween decorations come to life” were discovered in Hoschton, Georgia; they likely arrived via a shipping container from China or Japan. Since then, they have moved rapidly throughout northeast Georgia and into metro Atlanta suburbs – and more recently into the Carolinas. A Jorogumo is a spiderlike creature or goblin from Japanese folklore, hence the name. Alan speculates that powerlines are providing easy routes for the Joros to cross obstacles like roads and rivers, as they move
Meet Our New Arachnid Neighbors Giant Joro spiders have arrived in North Georgia, but impact is unknown tive spiders are harmless to people and will eat (the nasty) brown marmorated stink bugs, themselves an invasive that was accidentally introduced; our native spiders apparently have discriminating tastes and do not consume stink bugs. Joros also feed on mosquitos, flies, and yellow jackets. Impacts Unknown
quickly and efficiently into new territory. They also travel long distances (50 to 100 miles) by ballooning – using wind power by catching a breeze with the silk threads that they spin. And, like other spiders, they often hitchhike on cars and trucks. On a recent walk in Chicopee Woods in Gainesville, I observed my first Joro: a palm-sized female on a bright yellow, three-dimensional web of silk that was amazingly strong, as I learned by tugging on it – strong enough, I have read, to capture hummingbirds and massive enough to capture pollinating bees that help maintain genetic diversity in plants and ensure seed production for crops. Some good news is that these non-na-
While some are extolling the “pest control” benefits to be reaped from our new arachnid neighbors, others – including Dr. Bud Freeman with the UGA Odum School of Ecology – are cautioning that much still remains unknown about them. How will they affect local ecosystems? Will they outcompete and displace other orb weaving spiders? Will they reduce important insect populations? Should there be efforts to eradicate these trespassers in an attempt to control their populations, as some suggest? Joros represent yet another non-native species that must be monitored and evaluated for any unexpected economic and environmental consequences. In their homelands, these spiders are kept in check by local predators and defense mechanisms developed by their prey; however, in a new place, without those checks, they can spread widely, and sometimes with devas-
tating outcomes. How are invasive species defined and what other types have we experienced in Georgia, both currently and historically? The Georgia Invasive Species Task Force (gainvasives.org) describes them as non-native species that have been introduced – either intentionally or accidentally – into areas outside their natural ranges and that cause economic or environmental harm of impacts to human health. While most introduced species pose little threat to the environment, many constitute a significant risk. In fact, invasive species rank second only to habitat destruction as a threat to biodiversity – in other words, a threat to every living thing from humans to tiny organisms. In Georgia, we have seen the major impacts that invasives can have on forests, farmland and parks. What You Can Do If you spot a Joro spider, take a photo and tag it with the date and location. Then, send it to Dr. Richard Hoebeke at rhoebeke@uga.edu and/or post your observation on the iNaturalist app.
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NOVEMBER 2021 | 15
