Northern Beaches residents have reported watching hundreds of thousands of tiny spiders ‘parachute’ to shore, most of them across Manly and Dee Why, this week.
Dee Why resident Wayne Heisler said they were all over his suburb and in his beachside apartment on Monday. “You would just sit down somewhere and you’d find them crawling all over you,” he said.
Further south, girls training at Manly Life Saving Club confirmed they had spider webs blowing across their faces as they paddled five minutes out from the beach.
Lower Northern Beaches mum Kath Coulton said her daughter awoke to find her bedroom ceiling totally covered in little spiders on Monday.
Over at Shelly Beach local Keli Parkes said she was sitting on the sand when she noticed “white fluff flying through the sky”. “I had no idea what it was and had never seen anything like it before. It was very strange,” she told Manly Observer.
So what are they and why did this happen?
These tiny arachnids are most likely a variety of sheet-web weavers called money spiders. While the phenomenon is still not fully understood, certain weather events (say, heavy rain or consistently hot days) can spur the spiders into taking to the air for safer ground in what is known as a mass ballooning event.
The clever little critters send out silk strands when air currents are optimal which lifts them to higher ground.
Dieter Hochuli, Professor of Ecology at the Faculty of Science at the University of Sydney told Manly Observer that while the spiders could have theoretically come from anywhere in the world, it was quite likely there was a mass spawning event from across the Northern Beaches just as a prevailing wind kicked in – taking them up and out to sea then dropping them back to shore, to the horror of those covered in literal thousands of the crawlers.
“It’s hard to say exactly what type of spiders they are as many different varieties do a lot ballooning. There are over five thousand types of sheet web weavers but it is most likely a money spider,” he said.
“When they hatch, there’s usually lots of them all together and it’s quite dangerous for them. Often the big ones eat the smaller ones so to get away they try to find a new place to colonise,” he said.
The spiders throw a thin thread of silk from tubes on their rear end and catch a ride to safety, he said.
“None of these spiders are dangerous to humans, they are just trying to make a living like the rest of us,” he said, suggesting residents could just sweep the arachnids up with a duster or a tea towel and leave them in the garden.
“Though in reality most of them will die,” he added.
This is the first such event we could find recorded on the Beaches, though there was a significant ‘angel hair’ event in 2015 in Goulbourn, whereby hundreds of gossamer white threads were spotted floating through the air and settling on the ground after heavy rainfall.