Spiders arrive in balloons of fine silk

SILK ROAD: Millions of spiders have made new webs at Jordan Valley Road in Hikurangi. PHOTO/MICHAEL CUNNINGHAM

Millions of money spiders may have ballooned their way to Hikurangi but don't expect any money bags to be found on the swamp any time soon.

Silk sheets fluttered in the wind yesterday after the initial landing by the arachnids on Wednesday. Heavy rain early yesterday had caused some of the fine white-coloured sheets to disintegrate and experts estimated the rest would be gone over the next few days as the spiders made their new homes in the grass and scrub on the flood banks of Hikurangi Swamp.

The naturally occurring phenomenon and eye-catching sight might be an arachnophobe's worst nightmare but for those specialising in the bugs the latest landing is a delight.

Arachnologist Grace Hall, of Landcare Research in Auckland, said the mass movement of the tiny spiders happened every year in autumn after the spiders hatched.

She said if there were too many spiders in one area they would spin a fine silk balloon and drift on the warm thermals to new surrounds.

"It happens all the time across New Zealand and all around the world ... it's the way they move around."

The silk used in the balloons was known as Gossamer silk and was more noticeable if there was a slight amount of moisture in the air.

Mrs Hall said the floodwaters were not the reason for the move but may have been a coincidence.

The influx of eight-legged visitors to new pastures would not upset the ecosystem either, it was part of a natural progression.

Insects like the miniature silverfish were also hatching in the soil and provided plenty of food for the ravenous spiders.

They also fed on other bugs and if the food source started to run short the spiders would turn on each other and become cannibals.

"They go for anything that gets caught in their webs but like many spiders they can turn on each other to survive."

The term money spider covered about 30 different species and without seeing an adult specimen up close it was hard to determine exactly what spider it was, Mrs Hall said.

Jordan Valley Rd was festooned for about 75 metres on both sides with the webs.

Local farmer Ben Smith said he had seen the spiders take over before with paddocks being covered in the fine silk.