Navel orangeworm, Amyelois transitella (Walker) was intercepted at the Korean port of entry. It was detected by an inspection for a consignment of fresh oranges from the USA by the Busan Newport District Office, Yeongnam regional office, Animal Plant and Fisheries Quarantine and Inspection Agency on January 31, 2012. This is the first time that the larvae of this pest species has been detected on fresh oranges, although it has been occasionally detected on walnuts. This report aims to ensure biosecurity by providing diagnostic characters to identify the caterpillars and conducting an imported risk analysis on fresh oranges from the USA.