A bizarre and oddly beautiful display of spider webs have been woven across a large field along a walking trail in Cape Breton.

"Well it's acres and acres; it's a sea of web," said Allen McCormick.

He was out for a walk on the Summit walking trails in Scotchtown when the field of webs stopped him in his tracks.

McCormick said a light dew last week made the webs stand out.

"It was kind of breathtaking, actually. I've never seen anything like it. You see lots of nature, but I've never seen a field covered in web before."

McCormick started snapping pictures.

No one he talked to had any idea why the field had filled with webs so quickly.

"Maybe Spiderman does live in Cape Breton," joked McCormick.

'Mass dispersal events'

Prof. Rob Bennett may have the answers though; he's an expert on spiders who works at the Royal British Columbia Museum in Victoria.

Bennett examined McCormick's pictures. He said tiny, sheet-web weaver spiders known as Erigoninae linyphiidae most likely left the webs.

The little spiders are one or two millimetres long.

"For some reason, mostly unknown, these types of spiders are known to do these mass dispersal events. The spiders decide collectively that it's time to leave that area."

It's just the cumulative effect of all those spiders each producing a single line of silk. - Prof. Rob Bennett

Bennett said the spiders do that by casting a web net to catch the wind and float away in a process known as ballooning.

The webs in the field are the spiders' drag lines, left behind as they climb to the top of long grass to be whisked away by the wind.

"It's just the cumulative effect of all those spiders each producing a single line of silk and leaving it behind wherever they roam," he said.

"They might go backwards and forwards, up and down, sideways, they may jump over to another plant and that sort of thing. It doesn't take long for that number of spiders to produce quite a noticeable quantity of silk."

Bennett said it's a mystery why these spiders take off en masse.

It's believed that weather or a disruption to the spiders' environment causes them to leave, and researchers in the U.K. are trying to figure that out.

Bennett said people shouldn't be worried about running into millions of ballooning spiders, as they pose no risk to humans and should be considered friends.

"They're out there doing us a great service in terms of naturally controlling insect populations in forest, fields and agricultural systems," he explained.