Biosecurity New Zealand is confident the Queensland fruit fly is not established here, despite a fourth fly being discovered in Auckland yesterday.
A male Queensland fruit fly was found in Northcote yesterday - the third in the area.
It is the fourth Queensland fruit fly to have been discovered in the past two weeks.
Biosecurity New Zealand spokesperson Catherine Duthie said there was no evidence to suggest an established Queensland fruit fly population had been found.
"The proximity of these three detections in Northcote as well as the timing would indicate they are possibly from the same source," Dr Duthie said.
"We have investigated several hundred kilos of fruit collected in the area.
"We dissected this looking for eggs and larvae, and we have found no evidence of a population to date."
Dr Duthie said Biosecurity was increasing its zone of controls in the area, following the latest discovery.
"Because the new Northcote detection was just outside of the original A Zone, we have increased our A Zone slightly, which means the placement of additional traps.
"We did not need any additional staff to do this."
For a timeline of fruit flies found in Auckland this year, not including the 1 March discovery click here.