The Department of Conservation (DOC) says it has wiped out wasps during a trial involving a new bait specifically targeted at the species.
Wasps are estimated to cost the New Zealand economy more than $130 million a year.
DOC said wasp numbers fell by 95 percent when it used the protein bait, containing an insecticide called fipronil, at five different sites in the South Island.
A month after the trial, nests were completely under control.
That compared with wasp activity increasing by 160 percent at non-treated sites at the same time.
DOC scientist Eric Edwards said there was significantly more honeydew on trees in areas where wasps were killed, allowing birds and insects to thrive.
The department said it was considering using the bait on other conservation land next year.