Web of Mystery

December 2011

These are a couple of the pics I took of the extensive webbing and masses of spiders, at Carrs Creek in the Clarence Valley. The paddocks are located between a creek (Carrs Creek) and the Clarence River, and it’s common for them to be submerged during flood. The small spiders (or spiderlings?) were seen massing on the edge of the recent rising floodwaters. The webbing was then discovered as the water began to recede.

Answer

Queensland Musuem curator of arachnids, Dr Robert Raven says:

The spiders are wolf spiders of the genus Venatrix. They have been driven onto the vegetation from the ground by the flooding. They normally live in the leaves or in burrows in the ground. A survey in the UK reported that there are about a million spiders in each acre and by the look of the photo they are not far wrong. The spiders are not dangerous, but are an arachnophobe's nightmare.

What you can see in one of the photos are the spiders with their legs stretched out. What is happening is that the spiders are trying to escape this severe overcrowding and get to dry ground. Who isn't?

The spider silk is liquid when it is formed at the end of the body on the spinnerets. With a back leg, the drop is stretched and then becomes fibres and so it is pulled out from the spinnerets making a longer and longer thread in the wind. Finally, the pull on the silk is so strong that the spiders are straining to hold on, as in the photo. Eventually, the spiders release and fly into the air in a process called ballooning.

Photos courtesy of Josh McMahon

Hopefully, the updrafts carry the spider away to dry ground. Many spiders use the method routinely to disperse. Charles Darwin reported when he was 2000 miles from the nearest land that suddenly the rigging of the ship (The Beagle) was covered with the silk of thousands of tiny spiders. Eventually, these spiders get into the stratosphere where they are sometimes noted by pilots as the threads of silk cover the windscreen of the planes. They get reported quite frequently in western Qld and NSW by helicopter pilots as an Indian summer sweeps in an the warm updrafts are the trigger for the spiders to get airborne. It is a beautiful and amazing process, nothing to fear.
 

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