The Bay of Plenty Regional Council is conceding defeat in a battle to eradicate the Argentine ant.
Argentine ants have multiple queens and create giant colonies. There are currently 28 known sites in Tauranga, Mount Maunganui, Rotorua and Whakatane.
The council says it will now be directly involved in control operations only to protect sites of high value biodiversity.
However, it will continue to provide an ant identification service for people who are able to freeze samples overnight.
The council says a great deal of money has been spent, but it's highly likely that new arrivals will come from neighbouring regions.