IT’S the strange phenomenon everyone’s talking about. The unearthly sight of hundreds of gossamer white threads floating through the air and settling on fields and houses.

If you look closely, you’ll see small, black dots nestling in these shimmering trails. This is spider rain.

The latest arachnid shower took place in Goulburn, NSW, last week, with locals spotting what looked like vapour trails drifting down to cover the area, and then melt away.

Many feared an invasion of creepy-crawlies akin to something from a horror movie.

media_camera Floating webs blanketed North Wagga, NSW, after flooding in 2012.

Keith Basterfield, from South Australia, has been researching Australian “angel hair” for years, and has been contacted by people who’ve witnessed the rare natural event following the Goulburn reports.

The earliest was from the travel diary of a man driving through Albury in 1974, one came from a woman living in Yass, NSW, and another from a cyclist in Tasmania.

“What amazes me is the vast areas of coverage,” Keith told news.com.au. “A fall in Esperance [Western Australia] 15 years ago was 40 kilometres across and went on for four or five hours.

“People are always amazed, they don’t know what it is and they’ve never heard of it. It’s always early morning or afternoon when they see these parachuting spiders.”

media_camera The rare phenomenon has fascinated witnesses. Picture: Brad Newman

The astonishing spectacle usually occurs in May or August in Australia, when sunshine follows rainfall. It is rare because it requires an unusual weather pattern for this time of year, which is when spiders are hatching.

The spiderlings are light enough to float on threads, sometimes for hundreds of kilometres at up to 20,000 feet, according to Keith. They have even been spotted by aircraft.

Their long-distance travel enables them to migrate to new areas, partly for instinctual reasons and partly for food, with an increase of mosquitoes in rural areas at these times of year.

Once they land, the spiders disappear into the ground and the threads, made of protein, disintegrate until there is no evidence that anything has happened.

“Millions use this method to migrate,” said Keith. “But there are only a couple of species in Australia so it’s fairly rare to see.”

Any temperate part of Australia and other countries can experience the bizarre sight. Videos from 2013 show the flying spiders descending on Brazil and Texas, while in Denmark, researchers analysed the protein that makes up the webs to find out more.

“I’ve done historical research going back to as early as 1914 in South Australia,” said Keith. “There were about 20 falls in that time. I’m encouraging people to make videos and take photos as this is of interest to entomologists and scientists.”

If you have any spider rain photos or footage, contact emma.reynolds@news.com.au.

Originally published as Australia’s ‘spider rain’ explained