A single Queensland fruitfly has been found in a trap in Auckland and there's a warning New Zealand's fruit and vegetable industries could be devastated if the pests are breeding.

Primary Industries Minister David Carter has told parliament it's a potentially serious biosecurity issue and New Zealand's trading partners are being notified.

"We need to quickly find out whether we are dealing with a single inspect or whether a breeding population has been established, in which case an eradication response will start immediately," he said.

Labour's biosecurity spokesman, Damien O'Connor, says Queensland fruitflies are considered to be Australia's most serious insect threat to fruit and vegetable crops and could have a devastating impact on New Zealand industries.

"This is a very serious situation for New Zealand," Mr O'Connor said.

"An incursion is likely to have a significant effect on the economy with potential job losses and eradication will cost millions."

He says Mr Carter must immediately tell fruit and vegetable farmers what steps are being taken to prevent the flies spreading.

Mr Carter says he's well aware how serious the situation is.

"The important thing is how we react. While it is a serious potential issue I don't think we should overreact if we are dealing with a single trapping."