June 8, 2016 – 2:03PM
It’s an arachnophobe’s worst nightmare.
As the flood emergency continues to grip parts of Tasmania, thousands of tiny spiders have evacuated their waterlogged nests and burrows and taken refuge in the trees in the town of Westbury, near Launceston.
A resident, Ken Puccetti, took photographs showing several trees shrouded in white webs, with small black spiders clearly visible on the silk folds.
The spiders have thrown silk snag lines into the air to haul themselves out of the water in Westbury, Tasmania. Photo: Ken Puccetti
Graham Milledge, the collection manager in arachnology at the Australian Museum, said the spiders were escaping the floodwaters using a phenomenon known as ballooning. This occurs when small spiders throw out silk filaments and catch a ride on the wind to higher ground.
“People don’t realise how many spiders there are out there until you see events like this,” Mr Milledge said, after examining the photographs.
“These mass ballooning events are often associated with particular environmental conditions, for example the flooding that’s happening in Tasmania at the moment. I would imagine the spiders are just trying to get away from the water, basically.
In heavy rain, spiders fling themselves to safety by casting silk threads on top of trees and shrubs. Photo: Neil Richardson
“What they do is they climb up to a high vantage point – up to the end of a stalk of grass for example – and then they point their abdomen to the sky and let out a silk thread. The wind captures that and acts like a parachute and carries them off.”
A similar event occurred in Goulburn in the Southern Tablelands in May last year, when a resident, Ian Watson, described how his house looked as if it had been “abandoned and taken over” by the spiders.
“The whole place was covered in these little black spiderlings and when I looked up at the sun it was like this tunnel of webs going up for a couple of hundred metres into the sky,” he said at the time.
Spider webs cocoon trees during the floods in Westbury, Tasmania. Photo: Ken Puccetti
Mr Milledge said smaller species of spiders, often juveniles, were responsible for creating the webs.
“Generally they’re spiders that live on or close to the ground, for example money spiders, which build small webs in grass and so forth. Other spiders that have been known to do it are juvenile wolf spiders, which live on and in the ground,” he said.
Most of the spiders were considered “pretty harmless”, he said, and would disperse once the floodwaters receded.
“Personally I haven’t seen it before, but there have been other incidents. It’s not that common but it does happen every now and then,” he said.
Source : Sydney Morning Herald