A third Queensland fruit fly has been found in Auckland, in the same area where another one was discovered.
Authorities said the fly was trapped 113 metres from where another one was found in Northcote last week.
A trapping programme has been in place on Auckland's North Shore since a single male fruit fly was found in Devonport on February 14.
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The first fruit fly discovery prompted an investigation by Biosecurity New Zealand, and restrictions were put in place on the movement of fruit and vegetables in the area.
At the time, Biosecurity New Zealand spokesperson Dr Catherine Duthie said it did not mean there was an outbreak in the city, but that perspective may have now changed after the third was found.
She said if they become established in New Zealand, the Queensland fruit fly could "have serious consequences for New Zealand's horticultural industry".
"It can damage a wide range of fruit and vegetables and could lead to restrictions on trade in some of our horticultural exports."
There are 7500 traps set nationwide, which are checked regularly for fruit flies.
Two Tongan fruit flies have also been found recently in south Auckland, prompting a separate investigation.