Residents in eastern Victoria have been taken aback after waking up to vast, alien-like sheets of spider webs laying across paddocks and roadsides.
The East Gippsland town of Traralgon was one of the hardest-hit areas by recent flooding and wild weather. While its neighbour Sale avoided the brunt of the damage, flooded roads and paddocks disrupted the local spider populations, which are now seeking higher ground on road signs, trees and any tall grass they can find.
“It’s just incredible, when they blow in the winds they look like waves,” said Jena Beatson, who saw the spiders on her first trip into Sale from Longford after the roads were cut off by flood waters.
“It does look creepy the way it covers all the signs and everything. You can’t really see it in the photos but there are spiders all over. It’s like thousands and thousands of spiders.”
Actually, according to Dr Ken Walker, a senior curator of entomology at the Melbourne Museum, it is millions.
“It’s a semi-regular occurrence in Victoria in wintertime when we get most of our rain … Spiders can make a wide range of different silks and one of the silks they use for this behaviour – ballooning – it’s a very, very thin little silk that they use … to fly away with the breeze. They could fly 100km,” he said.
“What’s happened is there’s been a massive flooding event pretty quickly … so they’re using the ballooning not to escape for hundreds of kilometres, but to almost throw up a lasso on top of the vegetation. It hooks on to the tops of the vegetation because it’s lighter than air, and then they quickly climb up.”
When a huge number of spiders all do this at once, they end up hooking on to each other and can blanket the countryside.
This phenomenon, sometimes called the gossamer effect, is caused by “vagrant hunter” spider species, which live on the ground and do not build a web. They also do not create webs after ballooning away from a flood. In fact, Walker said, each spider only threw up a single thread, meaning every tiny line of silk represented a different animal.
“I would say millions of spiders [in the photos online],” he said.
East Gippsland is also experiencing a degree of mouse plague activity, which for a number of months has devastated regional New South Wales and has now crept across the southern border.
“Bunnings is selling out of traps and the farmers are having real problems with the sheds and that kind of thing,” Beatson said.
Photos of the spiders online have been accompanied by dozens of comments declaring that “the spider plague has descended too”, but Walker said these webs do not actually indicate any increase in numbers.
“It’s purely a result of the flooding event … What it shows you is the enormous amount, literally millions, of spiders that are there on the ground all the time. We just normally don’t see them because they’re under vegetation, on the leaves, under bark and things like that,” he said.
The spiders ballooning near Sale includes the red and black Ambicodamus species, and although their bites are not dangerous to humans, they can cause minor local irritation. Walker said people should not be worried though, as none of the highly venomous species would make up part of the net.
“It’s not dangerous at all. Most of these spiders, their fangs are probably too short to penetrate the human skin.”
Locals from all around Sale had been coming out to look at the spiders, Beatson said.
“It’s actually not a great drive at the moment, because everybody’s stopping and pulling over the side of the road to take photos,” she laughed.
But these blankets of silk will not last long.
“These threads are so thin, usually as soon as the first breeze comes along, they get quickly broken up and dispersed,” Walker said, encouraging those in the area to enjoy them while they lasted.
“[Across Victoria] we only really see it about once a year … It’s a beautiful event and it’s something that’s quite rare.”