Navel orangeworm damage to pistachio nuts was especially severe in portions of an orchard adjacent to blocks of infested almonds which served as the sources of immigrant moths. The degree of damage diminished as distance from the principal external sources of moths increased, reaching economically unimportant levels at ca. 500 m. Pest management programs for the navel orangeworm in pistachios should include reduction efforts in almonds when almonds border pistachio orchards.