Border staff at the Port of Auckland are on high alert after finding an Asian gypsy moth egg mass on an imported Japanese car.
The moths are considered one of the worst forest pests. They have caused widespread damage and severe losses in the Northern Hemisphere.
The Ministry for Primary Industries says quarantine inspectors have been on the look out after warnings from Japan of a heavy moth breeding season.
It says the discovery of the egg mass on the wheel of an imported car earlier in August shows New Zealand's biosecurity controls are working.
In 2003, a live adult gypsy moth was caught in an early warning trap in Hamilton. There was a large scale response by the then Ministry of Agriculture and Forestry. No more moths have been found since.