A single queensland fruit fly has been found in a surveillance trap in Auckland.
The fruit fly, found in Devonport, is now being investigated by Biosecurity New Zealand and additional fruit fly lure traps are being set to determine if other flies are in the area.
However this doesn't mean there is an outbreak, Biosecurity New Zealand spokesperson Dr Catherine Duthie said.
"It is vital to find out if this insect is a solitary find or if there is a wider population in Auckland that will need to be destroyed," she said.
"If it established here, 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 now legal controls to restrict the movement of fruit and vegetables in Devonport.
Dr Duthie said the controlled areas would stop any other flies getting out, if there were any more.
The restrictions mean no fresh fruit or vegetables are allowed to be moved out of the controlled area A, which centres around Kerr Street.
There's a larger controlled area which covers most of the peninsula, but applies only to fruit and vegetables grown within the area.
Dr Duthie said it was critical people obey the restrictions, which will be in place for a couple of weeks.
There are also restrictions on moving compost and green waste out of the areas.
In 2015, a Queensland fruit fly outbreak cost the government more than $1 million per insect to eradicate.
The fruit fly has been found six times before in northern New Zealand - in Whangārei and Auckland.