The European Commission requested the EFSA Panel on Plant Health to conduct a pest categorisation of Garella musculana (Erschov) (Lepidoptera: Nolidae), following a commodity risk assessment of Juglans regia plants for planting from Türkiye, in which G. musculana was identified as a pest of possible concern to the European Union (EU). Commonly known as the Asian walnut moth, this pest is native to Central Asia and develops on shoots, buds and fruits of Juglans species such as the English walnut, J. regia and the black walnut, J. nigra. Other reported host plants, such as Prunus dulcis and Populus spp., still require confirmation. The pest was first recorded in the EU (Bulgaria) in 2016 and was then reported in Romania in 2018 and Italy in 2021. This moth completes from one to four generations per year depending on environmental conditions (from valley to mountain forests and orchards up to an altitude of 2100 m). Eggs are laid in groups of 2–3 on young nuts or on buds of 1-year-old shoots. Neonate larvae usually enter the young nut through the peduncle. After fully exploiting one nut, the larva continues feeding in another one. Development takes 25–40 days. Larvae of the autumn generation do not enter the nuts, and so feed only in the pericarp. Larvae also often feed inside 1-year-old shoots or leaf axils. Larvae develop within the host but exit to pupate under loose bark or in deep cracks of bark. The pest overwinters at the larval or pupal stages. Plants for planting, cut branches and infested nuts provide pathways for entry. Climatic conditions and availability of host plants in southern and central EU MSs have allowed this species to establish and spread in Bulgaria, Romania and Italy. Adults can fly and the pest could spread naturally within the EU. Impact on Juglans spp. cultivated for fruit, timber and ornamental purposes is anticipated. Phytosanitary measures are available to reduce the likelihood of entry and further spread of G. musculana. This species meets the criteria that are within the remit of EFSA to assess for this species to be regarded as a potential Union quarantine pest.