Arachnophobes beware. There is a silent army on the move in flooded New South Wales.

Floodwaters have stirred up what appears to be millions of spiders around Wagga Wagga and the creepy crawlies are heading for higher ground.

Residents taking refuge from flood and spider in the Red Steer pub say you cannot walk down the road without swarms of tiny brown spiders crawling up your legs, and in their escape they have left entire paddocks and trees swathed in silver silk.

Dennis Lane, who lives at Cartwrights Hill in north-east Wagga, says the spectacle has attracted many visitors to the area to take photos.

"It's all silver. It's like snow in the trees. With the wet it's all silk," he said.

"Just down the bottom of the hill from my place, the trees are covered in them. They're just all walking out of the water down the road."

When asked to estimate how many spiders there were, Mr Lane replied: "Well, have you ever won the lotto? Millions."

He says like many of the residents of Wagga Wagga, the spiders are seeking refuge too.

"I went down and said 'what are all these little things here?', and you see them all, all little tiny ones. They've got to try and protect themselves too so they're looking for dry land like everyone else," he said.

But Mr Lane says he would rather the spiders than some of the other creatures washed out by the floods.

"I'd rather them than snakes. I've seen snakes swimming in the river. Geez they can swim too, they're beauts - better than Ian Thorpe," he said.

"[The spiders] are harmless. They're not funnel webs. I think they're harmless anyway, I hope they're harmless - they were heading up my way."

Harmless

And according to spider expert Graham Milledge, the spiders are most likely harmless.

Mr Milledge is collection manager in arachnology at the Australian Museum.

He says the spiders look like wolf spiders.

"It's not possible to say precisely what they are unless we can get some samples and examine them," he said.

"After seeing the photos, they look to me like they might be juvenile wolf spiders.

"Wolf spiders are a very common type of spider in open country like that. They're ground-dwelling spiders."

Mr Milledge says the silky layer the spiders are leaving across parts of Wagga Wagga is a product of "ballooning".

"One way spiders can move around is by what they call ballooning, so they let out lengths of silk in the hope that the wind will catch them and carry them away to another place," he said.

"But if there's not enough wind around, what happens is they don't get very far and they all end up in the same place. They'll keep trying and that's why you'll get all that silk."

While the spiders are harmless to humans, Mr Milledge says the brown army could start turning on each other if the floodwaters do not recede and allow them to disperse.

"Potentially they could eat each other in a situation like that," he said.