The Cypress aphid (Cinara cupressivora) is considered as one of the most important invasive pests in the world attacking Cupressaceae family. In Ethiopia it has caused over US$10 million worth of damage to Cypress plantations across the country. The recent study was done on assessment of Cypress aphid infestation and its natural enemies on cypress plantation of Jibat and Gedo district, Oromia region, Ethiopia. The general objective was to assess the cypress aphid infestation, damage and its natural enemies. Stratified random sampling was used, where 10% of plants were considered as a candidate from one quadrant (100m2). Results from this study indicated that Cypress aphid was un-equally distributed throughout the altitudinal ranges and age classes. The higher altitude had more Cypress aphid than lower and middle altitude and the abundance was statistically significant in both studied area. Observation showed that the young age class was more attacked by Cypress aphid than middle and old age classes. Natural enemies were un-equally distributed throughout the altitudinal ranges and age classes of Cupressus lusitanica. From the study it can be concluded that the higher altitude and young age class were more infested. In order to deal with the problem of the Cypress aphids at Jibat and Gedo Cypress plantation, broadly management measures should be intensified starting with young age classes and at higher altitude.

Keywords: Cinara cupressivora, Cupressus lusitanica, altitude, age classes, damage intensity, Cypress plantation.