Invasive Argentine ants are a worsening problem in Rotorua, according to a local pest buster.
Bay Pest Services manager Chris Brunel said in the last couple of weeks the company had started to get domestic calls and there had been a number of buildings in the city which had experienced problems.
The ants had been a problem in Ohinemutu right from the outset, since it was a thermal area, he said.
"They like the warm ground, it replicates their home environment."
He said managing the ants could be an expensive exercise.
Mr Brunel emphasised he did not want to seem like he was scare mongering, but was concerned "this beautiful city" could have a problem.
"I feel as though the public needs to be more aware of this issue."
Argentine ants had been a biosecurity breach and were one of the 10 most invasive species in the world.
The ants would bite and had been known to swarm into trees and kill baby birds in nests, he said.
"If they get into your house they can be a real issue to try and get rid of."
He said landowners could keep an eye out for them in plants and around their sections.
At first glance they looked like a standard ant, but they were rusty in colour and looked a bit hairy, often out in large numbers, Mr Brunel said.
Bay of Plenty Regional Council biosecurity manager Greg Corbett told the Rotorua Daily Post Argentine ant control was the responsibility of the landowner under its current Regional Pest Management Plan.
"Bay of Plenty Regional Council continues to provide advice to landowners on control options, this has not changed since 2011."
He said the regional council funded initial ant baiting trials in the Bay of Plenty in the early to mid 2000s.
"Over the last year we have received just two inquiries from Rotorua based residents regarding Argentine ants, we have no evidence of the problem getting significantly worse.
"However, our Regional Pest Management Plan is scheduled for review over the next 18 months."