Rat numbers have exploded across New Zealand and it is no different in Rotorua with some saying numbers are at a 48-year high.
Pest controllers' phones are ringing off the hook due to an outbreak caused by a mega mast Forest and Bird say.
A mega mast is an over-abundance of plants that have a high seed production, in turn providing food for pests.
The problem began close to four months ago and there are ways to avoid a problem like this in future said Alpeco managing director Heiko Kaiser.
"There are more rats and bigger rats because their stomachs are full."
Kaiser said putting a programme in place and making a conscious effort to become a cleaner nation would bring New Zealand closer to the goal of Predator Free 2050.
"Just throwing toxins down the hill, no. We need to lead them to the traps."
"What makes it harder this year is the amount of food for them, so let's outsmart them."
Rat numbers were at a 48-year high, Bay Pest Services manager Chris Brunel said. He had been taking calls all morning.
"They have been seen running through the car park building and through the CBD, it's crazy."
He said the mega mast was the cause as the abundance of food supply and aided the rats, which bred every 30 days.
"It has never been this bad before.
"Even my supply company has run out and we have to order the bait from Australia."
The mega mast mainly affected beech trees which were not overly prominent in Rotorua but Department of Conservation community supervisor Carrie Abbott said other heavy-seeding species were supporting predator growth.
"Forest seeding provides a bonanza of food for native species but also fuels rodent and stoat plagues that will pose a serious threat to native birds and other wildlife as predator populations build up to next spring and summer.
"Given the breeding rate of rodents and mustelids, any event that supports their breeding is a setback for conservation and for Predator Free 2050."
She said fortunately, Rotorua was seeing an increasing number of community-led projects that were stepping up to protect the environment.
Rats threatened the survival of many native species as they ate almost anything, including native species and their food sources.
And the implications of the pests had been seen on Mokoia Island since the end of April.
The Mokoia Island Trust had to initiate an incursion response after signs of rats and mice were discovered on their tracking cards.
Mokoia was the only inland island currently breeding species and as a result Trust chairman Rawiri Bhana said at the time boat landings could only be authorised by the Island's Board of Trustees and quarantine checks were a requirement.
Unfortunately, the island's close proximity to the mainland leads to frequent unauthorised landings, he said.
"What may seem rather innocent such as parking up your boat to have lunch can actually have devastating effects on Mokoia."
There were still traces of mice on the island which they were working to eradicate.
How to protect your home from rats
The Ministry of Health provides tips people can follow to control these pests and keep their family safe.
Baits and traps
• Poison is an effective way to control rodents and can be purchased from supermarkets and hardware stores. Always read and follow the instructions.
• Rat and mouse traps can also be used and are available from supermarkets and hardware stores too.
Removing food sources
• Store rubbish in secure metal or thick plastic containers with lids.
• Do not leave plastic rubbish bags outside overnight, if possible.
• Keep the inside and outside of your home clear of food scraps and rubbish.
• Do not leave extra pet food out.
Reducing their habitat
• Remove weeds, overgrown grass, rubbish and other materials that could provide hiding places for rodents.
• Secure any gaps or cracks in your home to stop rodents getting in.
Source: Ministry of Health