Hamilton has been declared free of the destructive asian gypsy moths after no sightings of the pest for two years.
Since spraying, part of a $5.4 million eradication Ministry of Agriculture and Forestry (MAF) programme, was done in October and November 2003 trappings had confirmed the moths had gone, BiosecurityMinister Jim Sutton said today.
The only moth ever found in Hamilton was in March 2003.
The time passed would have covered two generations of the moths, Mr Sutton said in a statement.
"International recommendations for gypsy moth are that where no further activity is detected for two generations after treatment, then eradication can be declared successful."
As well as aerial spraying, the eradication effort included ground searching, pheromone trapping in Hamilton and surrounding satellite towns, mass trapping, public awareness, and the establishment of a Controlled Area and movement controls on host vegetation.
Mr Sutton thanked the people of Hamilton for putting up with the inconvenience and discomfort during the eradication effort.
There had been opposition to the spraying and a group, Waikato Against Toxic Chemicals and Hazards (Watch), formed to fight it.
It took the MAF to court to try stop the spraying but failed.
Restrictions - such as a ban on moving vegetation or garden waste outside the city unless inspected by MAF - were now lifted but monitoring would continue, Mr Sutton said.
