Damages produced by eriophyid mites to Olea europaea subsp. europaea cv. arauco have been known for many years. In a previous publication, the presence of Aceria oleae (Nalepa) and Oxycenus maxwelli, (Keifer) in Argentina was reported, but the species was not definitively identified. In the past five years, damage caused by this mite to leaves, flowers and fruits in many production areas was very high, leading to the need for further investigations about this mite, the most numerous mite species on this plant in Argentina. The present paper is divided in three parts: a) a morphological characterization of A. oleae based on specimens collected in Argentina, with the use of SEM; b) a study of its life cycle; and c) an illustration of its damage to leaves and fruits. The morphological study led to the confirmation of the identity of the species and to the determination of morphological aspects not previously mentioned in the literature. Life cycle and damage were observed to be similar to what has been previously mentioned in the literature for the same mite in other countries.