Dunedin pest controller Dave McPhee, of DM Holdings, said it had been "an exceptional season for spiders".
It was the worst season for arachnids in his 20 years of pest control.
There seemed to be an influx of white-tailed spiders, his company having being called to about 20 jobs for them this summer. Most years they only had about five call-outs.
He had heard about several people being bitten, including one person who had been nipped on the toe while putting on a shoe.
Some Dunedin residents had also got a fright a fight to find white-tailed spiders in their bedding.
"It’s just been so bad this year," Mr McPhee said.
While most white-tailed spider bites were not particularly serious, some people could have a bad reaction and end up in a hospital emergency department, he said.
Summit Pest Management owner Adrian Adamson said many people had been getting back from holiday to find their houses looking untidy as they were inundated with spider webs.
While white-tailed spiders were the species best known for their bite, tunnel web spiders, which were often found in Waverley, Andersons Bay and Brighton because they liked the sea breeze, could also bite a human, Mr Adamson said.
The fearsome-looking species grew to the size of an old 50c coin, he said.
University of Otago arachnologist James Crofts-Bennett said the year had been "absolutely perfect for spiders".
The weather had been humid and warm, with rain in the spring and summer.
"The local spider population has been exploding," Mr Crofts-Bennett said.
It was also not so hot that spiders, which had lungs on the outside of their bodies, would dry out.
He estimated there were more than 100,000 spiders at the rail bridge where State Highway88 crossed the Water of Leith.
They had not died off over winter, as temperatures had remained relatively mild, so there had been a double breeding season.
Dunedin was home to more than 100 varieties, especially in its Town Belt and gardens as spiders loved having a diversity of plants.
There were about 2000 different types of spider across the country.
Katipo spiders lived around the city, but while they were venomous they did not pose much of a threat because they were so docile, Mr Crofts-Bennett said.
Tunnel web and vagrant spiders were both native, scary-looking and quite docile, but would bite in self-defence.
