The EFSA Panel on Plant Health performed a pest categorisation of Nemorimyza maculosa (Malloch) (Diptera: Agromyzidae) for the European Union (EU). N. maculosa is an oligophagous pest; cultivated hosts include Chrysanthemum, lettuce and other Asteraceae although there is little evidence of recent impacts. N. maculosa occurs widely in the Americas and is present on the island of Madeira (Portugal), where it is under official control. N. maculosa is not known to occur in mainland Portugal based on surveys. N. maculosa can have multiple overlapping generations per year. Eggs are inserted into the leaves of host plants. Developing larvae feed within leaves causing blotch mines. Pupation takes place in the soil or under debris on the ground. Immature stages on leafy host plant material such as Chrysanthemum cut flowers provide potential pathways for entry into the EU. Human‐assisted movement of cut flowers, fresh leafy hosts for consumption and plants for planting with foliage are considered the main pathways for entry. Climatic conditions and the wide availability of cultivated and wild host plants provide conditions to support establishment in the EU in the open and in greenhouse. The extent of potential impacts on hosts such as ornamental Asteraceae and lettuce in the EU is uncertain. N. maculosa is regulated in the EU by Commission Implementing Regulation 2019/2072 (Annex IIA) where it appears using a synonym, Amauromyza maculosa. Within the Regulation, the import of soil or growing medium, from third countries other than Switzerland is regulated and therefore prevents the entry of N. maculosa pupae. All criteria assessed by EFSA above for consideration either as a potential union quarantine pest or as a potential regulated non‐quarantine pest were met.