Huge, Flying Joro Spiders On the Move, but Little To Fear, Scientists Say

Midwesterners in the US might remember the summer of 2024 for its swarms of cicadas. But arachnophobes on the East Coast may well whisper about it as the “Invasion of the Joro Spiders.” Fortunately, scientists say, there’s little to fear. And there's lots to learn from the species, too.

Yes, Joro spiders are big. They have legs longer than the average human finger. Yes, like most spiders, they’re venomous. And yes, they fly — sort of. 

Baby Joros move about by “ballooning,” or spinning “silk webs that act as a parachute. It lifts them (upward) and carries them into the air,” spider expert Michael J. Raupp told ABC News. Raupp is an entomology professor. He teaches at the University of Maryland.

Joros are spreading up the Eastern seaboard swiftly. They're expected to extend their dominion as far north as New York City this year. Yet, for all their horror-movie traits, they’re pretty harmless, experts contend. 

“My sense is people like the weird and fantastic and potentially dangerous,” David Nelsen, a professor of biology at Southern Adventist University, told The Associated Press. “This is one of those things that sort of checks all the boxes for public hysteria.”

Joros are timid by nature. They're far more likely to scuttle away from a human hand than to bite it. It's true that the yellow-striped spiders are an invasive species, coming to the US from Asia. But they pose little threat to local ecosystems, biologists say. In fact, they may even help by being a hefty snack for native birds and other predators.  

Reflect: Describe a time when you encountered a new or unfamiliar spider or insect. What was your initial reaction, and how did your view of the creature change afterward?

Photo of a joro spider from Wikimedia Commons courtesy of Pamsai.