Welcome to Australia, where even the rain is spiders

A phenomenon known as spider ballooning has covered a regional Australian city in silky "Angel Hair" webbing.

Michelle Starr Science editor
Michelle Starr is CNET's science editor, and she hopes to get you as enthralled with the wonders of the universe as she is. When she's not daydreaming about flying through space, she's daydreaming about bats.
Michelle Starr
3 min read

Spider silk in Albury in May 1974. Image by Kevin Dixon via Keith Basterfield. Used with permission of Keith Basterfield

Spider web is pretty incredible stuff. It can be sticky or smooth, thick or thin. It has a tensile strength stronger than steel, and is tougher than Kevlar, and spiders use it for many purposes: cocoons, nest lining, nets for catching prey. And, as it turns out, they make nifty balloons for baby spiders seeking fame and fortune (or just better hunting) in the big wide world.

This behaviour is called, funnily enough, ballooning, and last week it shrouded the city of Albury in regional New South Wales, Australia, in silky white webs crawling with teensy tiny spiders.

"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 spider webs up in the air and use them as a parachute to detach themselves from the ground and move in large colonies through the sky," Keith Basterfield, who studies the phenomenon, explained to the Goulburn Post.

"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...It tends to happen a couple of times per year, usually on clear days with slight winds."

This phenomenon is known as "Spider Rain" or "Angel Hair" for the silky threads the spiders trail behind them, and it doesn't just happen in Australia. Spiders around the world have been spotted flying through the air on their gossamer balloons (Walt Whitman even wrote a poem about it).

What is unusual in the Albury event is the sheer number of baby spiders involved -- assisted by the ideal weather conditions, which most often take place in the area in May and August.

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To balloon, the tiny spider will find a launching point and stand on its tippytoes (spiders don't have toes, but the behaviour is called "tiptoeing"), sticking its spinnerets into the air, releasing very fine silk known as gossamer into a balloon. This is picked up by slight winds, and the spiders are dispersed to new homes, sometimes for weeks over a distance of many kilometres.

This allows spiders to be scattered all over the world -- why they appear even in remote locations, such as Antarctica (although they tend to die there rather than live a long and productive spider life).

However, should the wind change, the spiders can be scooped up and put down all in the one place, rather than more evenly scattered.

Basterfield has been documenting the phenomenon since 2001, although he has collected accounts as far back as 1920. His document includes eyewitness accounts of the spider balloons, location, frequency, time of day, duration, temperature, wind direction and speed, and cloud cover. Anyone who has observed the phenomenon in the area has been invited to contact him directly.

Although Australia is home to some of the most venomous spiders in the world, the tiny aeronauts are not among them, and disperse to new homes after a few days. The video below shows young Metellina segmentata spiders tiptoeing and ballooning in Derwitz, Germany.