The Ministry for Primary Industries says more than 2000 stink bugs were found on four bulk carriers of cars from Japan since February.
An MPI spokesman said 8300 vehicles were turned away at Auckland's port, leaving people waiting weeks to pick up their new vehicle.
Three of these vessels carrying the brown marmorated stink bug had since returned and discharged their cargo, subject to strict biosecurity conditions.
The fourth vessel was scheduled to return on Thursday and would undergo similar measures, including fogging with insecticide.
MPI said 2218 individual stink bugs had been detected this season.
"The number of detections has been going down as the season draws to a close. The high-risk period is September to April, which is when stink bugs in the Northern Hemisphere are more likely to hibernate in cargo bound for New Zealand."