Earlier this month, the residents of Goulburn – a small town in Australia’s Southern Tablelands – were spooked to discover their properties blanketed by millions of tiny spiders and mounds of their silky threads. The spiders had apparently rained down from the sky, silken thread and all, a phenomenon known as “Angel Rain”.
“Anyone else experiencing this Angel Hair or maybe aka millions of spiders falling from the sky right now?” wrote resident Ian Watson on the Goulburn Community Forum Facebook page. “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!”
That sounds positively frightful, but experts say that arachnid rains are actually a natural phenomenon, and not as uncommon as you’d think. It is referred to as ‘spider rain’ or ‘angel hair’ in scientific circles, and is actually a form of spider transportation called ‘ballooning’.
“Ballooning is a not-uncommon behavior of many spiders,” retired arachnologist Rick Vetter told LiveScience. “They climb some high area and stick their butts up in the air and release silk. Then they just take off. This is going on around us all the time. We just don’t notice it.”
It’s understandable that we never notice spiders ballooning, because they’re not always doing it at the same time and in the same place. What’s happened in the Southern Tablelands is that millions of spiders started ballooning at once, naturally creeping out residents.
“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,” said biology professor Todd Blackledge of the University of Akron in Ohio.
He added that certain species of small spiders and tiny hatchlings of larger spiders generally balloon in May and August in New South Wales. But an abrupt weather change this month may have carried the migrating spiders up and away, and then back down to earth in large groups. “They fly through the sky and then we see these falls of spider webs that almost look as if it’s snowing,” South Australian retiree Keith Basterfield told Gouburn Post. “We see these vast areas of baby spiders, all coming down at once in the late morning or early afternoon. You can know this has happened by either seeing it or spotting what looks like long threads of cotton telegraph poles, power lines and houses.”
Thankfully, none of the ballooning spiders are poisonous or pose a threat to humans. “There’s a tiny, tiny number of species that have venom that’s actually dangerous to people. And even then, if these are juvenile spiders, they’re going to be too small to even bite, in all likelihood,” Blackledge told LiveScience. He did add that such a huge group of spiders could block sunlight, causing damage to crops.
While the bizarre phenomenon has a scientific explanation, having your entire town shrouded in spider webs is surely a surreal experience. Ian Watson, who was later interviewed by the media, said: “The whole place was covered in these little black spiderlings and when I looked up at the sun it was like this tunnel of webs going up for a couple of hundred metres into the sky. But at the same time I was annoyed because you couldn’t go out without getting spider webs on you. And I’ve got a beard as well, so they kept getting in my beard.”
Interestingly, there’s a phenomenon opposite to Angel Hair, which can occur at around the same time as ballooning, after heavy rains or a flood. “When the ground gets waterlogged, the spiders that live either on the surface of the ground or in the burrows in the ground, come up into the foliage to avoid drowning,” said Australian naturalist Martyn Robinson. These ground spiders also throw silk ‘snag lines’ up into the air, and when they catch, use the lines to come up from the ground to avoid drowning. “You end up with thick silk roads, criss-crossing finer silk lines to to produce this interwoven shroud.”
“There’s nothing to worry about,” Robinson said. “They’ll all disperse once the weather conditions warm up.”
Here’s a video explaining the fascinating Angel Rain phenomenon:
