This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: When Joro spiders first arrived stateside more than a decade ago, scientists worried the massive black-and-yellow spiders would gorge themselves on the same bugs as native spiders (or even the native spiders themselves). If the invasive arachnids did make massive meals of Georgia's insects, the local orb weaver population—already facing dangers from insecticide and pesticide use—could suffer.
But a new study from the University of Georgia may ease some of those concerns. Published by PLOS One, the study was co-authored by Valdosta State University's Erin Grabarczyk. "In terms of direct competition for food, our study suggests Joro spiders eat different insects and a wider variety compared with native orb weavers," said Jason Schmidt, co-author of the study and a professor of entomology in UGA's College of Agricultural and Environmental Sciences.
The researchers analyzed the stomach contents of more than 200 Joro spiders from 33 sites across Georgia and South Carolina. They compared DNA fragments found in the digestive tracts of these spiders with those from more than 140 native orb weavers across the two states. While Joros do eat some of the same insects as orb weavers, the species' diets differed significantly, the study found.
In fact, Joros preyed on 26 unique species that the native spiders didn't touch, including bugs such as leafhoppers and aphids. Native spider species had the same diet regardless of whether Joros were present in the area, the study found. This finding suggests that Joros aren't necessarily making it more difficult for orb weavers to find their favorite snacks.
With their large, sticky webs and giant size, some people worry that the new spider species would prey on monarch butterflies, adding yet another danger to the many already facing the imperiled species. But the current study found Joros aren't eating a lot of butterflies, monarch or otherwise. "They're feeding on things that we would consider pests," Schmidt said.
For the size of the spider, it looks kind of like popcorn." They are, however, taking up a bunch of physical space. "Joro spiders make these crazy-looking yellow webs that are often tangled with other webs," Schmidt said. "That style of building is quite different from other spiders." But you can often find other native spiders in webs right next to them, Schmidt said.
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