Biosecurity officials have intercepted an Asian gypsy moth egg mass during border checks on an imported Japanese car at the Ports of Auckland.
Ministry for Primary Industries spokesman Stu Rawnsley said staff at the port have been on high alert for such masses following reports from Japan that this year's moth season is likely to be "heavy".
"We have also had reports from Canadian and United States authorities that the number of egg masses on vessels arriving in their ports from Asia is increasing."
Mr Rawnsley said inspectors pay particular attention to vessels that have visited high-risk ports.
"The moths are attracted to vessels at night and lay eggs behind light fittings and inside hatch covers where they are open for loading cargo."
Asian gypsy moths are considered internationally to be one of the most serious of all forest insect pests. They have caused widespread damage and severe economic impacts in the Northern Hemisphere.
In March 2003 a live adult gypsy moth was caught in an early warning trap in Hamilton. The find resulted in a large scale response by the then Ministry of Agriculture and Forestry. No more moths have been caught since then.