Opomyzoidea

Aulacigastridae is a very small family of flies known as sap flies. The family Stenomicridae used to be included within this family, but was moved by Papp in 1984. They are found in all the Ecoregions.

The Megamerinidae are a family of flies (Diptera) with about 11 species in three genera. They are small and are marked by an elongated, basally constricted abdomen. The family has been variously placed in the past within the superfamilies Diopsoidea, Nerioidea and more recently in Opomyzoidea but the evolutionary relationships remain unclear.

The Opomyzoidea are a superfamily of flies.

Neurochaetidae is a family of flies belonging to the order Diptera. These flies are also known as upside-down flies because they maintain a "head downwards" orientation while walking on vertical or steeply sloped surfaces. Neurochaetids date back to the Eocene–Oligocene boundary, with fossils of the extinct genus Anthoclusia in Baltic amber described by Willi Hennig, and the extant genera are native to the Old World tropics and subtropics.

Neminidae is a family of flies belonging to the order Diptera.

Fergusonina, the sole genus in the family of Fergusoninidae, are gall-forming flies. There are about 40 species in the genus, all of them producing galls on Eucalyptus, Melaleuca, Corymbia, and Metrosideros species (all in the family Myrtaceae) in Australia and New Zealand.

Stenomicridae is a family of flies belonging to the order Diptera. Flies in this family are yellow in color and easily mistake for Cecidomyiidae. The family is found in Europe.