A new venomous spider has officially made New Zealand home.

The noble false widow spider is one of the world's most invasive arachnids.

It was first seen last year in Porirua, and has since been spotted in Christchurch, Nelson, Waikato and Northland.

While bites are rare, infections from their bites don't always respond well to treatment.

Researchers say it appears to be thriving in urban environments, particularly around gardens and outdoor furniture.

It's most often found under pot plants, tarpaulin and in fence crevices.

Male spiders can be seen at night on exterior walls or the ground.

Massey University evolutionary ecologist Steven Trewick says its association with antibiotic-resistant bacteria is particularly concerning.

"Although considered less dangerous than black widows, the venom of Steatoda nobilis contains similar toxins."

It's not an aggressive spider, but it will bite in defence.

Symptoms of a bite include swelling, redness and pain.

Though some spider bites have been linked to tissue necrosis, nausea, hypotension, impaired mobility and secondary bacterial infections that may be resistant to standard antibiotics.

Researchers are asking people to upload suspected sightings of this spider to iNaturalist NZ to help them discover the extent of the invasion.

-RNZ