Millions of spiders just rained from the sky in Australia

Millions of tiny spiders recently fell from the sky in Australia, alarming residents whose properties were suddenly covered with not only the creepy critters, but also mounds of their silky threads. But that's not where the frightful news ends: Experts say that such arachnid rains aren't as uncommon as you might think.

This month's spider downpour in the country's Southern Tablelands region is just the most recent example of a phenomenon commonly known as "spider rain" or, in some circles, "angel hair," because of the silky, hairlike threads the spiders leave behind. Ian Watson, who lives in the region affected by the spooky shower, took to Facebook to describe what this strange "weather" looks like, according to the Goulburn Post.

"Anyone else experiencing this "Angel Hair" or maybe aka millions of spiders falling from the sky right now? I'm 10 minutes out of town, and you can clearly see hundreds of little spiders floating along with their webs and my home is covered in them. Someone call a scientist!" Watson wrote on the Goulburn Community Forum Facebook page.

So, here at Live Science, call a scientist (or two) is exactly what we did. Rick Vetter, a retired arachnologist at the University of California, Riverside, said Watson and his neighbors likely saw a form of spider transportation known as ballooning.

"Ballooning is a not-uncommon behavior of many spiders. They climb some high area and stick their butts up in the air and release silk. Then they just take off," Vetter told Live Science. "This is going on all around us all the time. We just don't notice it."

The reason people don't usually notice this ingenious spider behavior is that it's not common for millions of spiders to do this at the same time, and then land in the same place, said Todd Blackledge, a biology professor at the University of Akron in Ohio.

"In these kinds of events [spider rains], what's thought to be going on is that there's a whole cohort of spiders that's ready to do this ballooning dispersal behavior, but for whatever reason, the weather conditions haven't been optimal and allowed them to do that. But then the weather changes, and they have the proper conditions to balloon, and they all start to do it," Blackledge told Live Science.