spider town
Spider webs covering Wagga Wagga following floods (representational image)Reuters

It rained spiders in a town in Australia, with millions of baby spiders falling from the sky during a phenomenon called Angel Hair.

The town of Goulburn in New South Wales witnessed the occurrence last week, with a blanket of spiders coming down from the Southern Tablelands sky, the Goulburn Post reports.

Keith Basterfield, who has been researching Angel Hair for over 10 years, said the spider rain is a natural migration phenomenon.

"What happens is that during a particular time of the year, particularly in May and August, young spiders in the Outback somewhere throw these threads of spiderwebs up in the air and use them as a parachute to detach themselves from the ground and move in large colonies through the sky," he said.

"They fly through the sky and then we see these falls of spider webs that look almost as if it's snowing. We see these vast areas of baby spiders, all coming down at once in the late morning or early afternoon.

angel hair
A paddock in Albury, New South Wales, Australia in May 1974Keith Basterfield

"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. It tends to happen a couple of times per year, usually on clear days with slight winds." He said the conditions were just right in Goulburn for the rain of spiders to take place.

Locals took to the town's community Facebook page to report events: "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," resident Ian Watson said.

"If you look toward the sun there are millions of them and really high up here, like over 100m or more up, there is also a cotton like substance coming down that is kinda like spider web but not exactly."

Another woman said she saw what looked like silk thread floating through the sky for half an hour: "It was quite amazing," she said.

Australia Museum Naturalist Martyn Robinson told the Sydney Morning Herald that two migration techniques explain why it appears to rain spiders.

A dispersal technique called ballooning is often used by baby spiders, where they climb to the top of vegetation then releases a stream of silk that catches in the wind, carrying the spider away.

spider rain
Wild plants are covered in spiderwebs, formed as spiders escape from flood waters, in Wagga WaggaReuters

"They can literally travel for kilometres... which is why every continent has spiders. Even in Antarctica they regularly turn up but just die," he explained. "That's also why the first land animals to arrive on new islands formed by volcanic activity are usually spiders. You can have entire fields and paddocks and trees festooned with this gossamer or Angel Hair, as some people call it."

A second phenomena that can occur at the same time as ballooning normally happens after heavy rain or floods: "When the ground gets waterlogged, the spiders that live either on the surface of the ground or in burrows in the ground, come up into the foliage to avoid drowning."

The spiders will also throw silk lines up into the air to haul themselves from the ground: "Everywhere a spider goes it leaves a trail of silk, so if it falls off it can get back to where it started. If they use somebody else's silk line, they put their silk line over that. You end up with thick silk roads -- criss-crossing finer silk lines to produce this interwoven shroud. It's all very practical but to our eyes it looks quite beautiful."