Community groups say they need help from aerial 1080 to combat the swelling number of rats.
New Zealand is currently in the midst of an explosion in the rat population brought on by a 'mega-mast' year, where plants produce more fruit and seeds.
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Rats taking advantage of the extra food have multiplied in huge numbers and overrun normally relatively pest-free urban areas.
Forest and Bird conservation advisor Kevin Hackwell told The AM Show community trapping groups had been overrun. Northland's Bay Bush Action has recently caught its 10,000th rat from the 250-hectare section it looks after, but are still seeing thousands more.
"They're saying that they're seeing a tsunami at the moment, a tsunami of rats coming through because of the mega-mast.
"It's taken them eight years to get 10,000 rats, they could do that in an hour with aerial 1080."
Use of the toxin has been controversial, but Hackwell said 1080 is one of the best tools New Zealand has when these mega-masts happen.
- Hordes of rats the size of cats infest Auckland suburb of Titirangi
- Rat infestation not confined to Titirangi as populations double across New Zealand
"It breaks down in the environment, doesn't accumulate up in the food chain, it's just a really good toxin.
"It's particularly good at going for mammals and of course in New Zealand, the only mammal we have that's native is our species of bat, so it's a useful toxin because the things we want to kill is the rats and the stoats and the possums that are in our forests."
New Zealand - already one of the world's biggest users of 1080 - might need to use even more in the future. Hackwell says mega-masts will get more frequent with climate change.
Newshub.
