Spermatozoa from seven gall‐midge species, representing the supertribes Lasiopteridi and Stomatosematidi, have been examined by electron microscopy and compared to the spermatozoa of 30 previously examined gall‐midge species of the subfamily Cecidomyiinae. Derived characteristics of all examined representatives of this subfamily are the lack of acrosome and the absence of accessory tubules in their axoneme. The sperm axoneme ofDidactylomyiahas a unique ‘9 + 5 pattern’, i.e. with 9 outer doublets and 5 inner singlet microtubules. Unlike other members of Cecidomyiinae,Didactylomyiahas retained some plesiomorphic traits, namely crystal containing mitochondria and a homogeneously condensed nucleus.Stomatosemahas a 10 + 0 axoneme and an irregular nuclear condensation. Thus,Didactylomyiamay serve as an useful outgroup for phylogenetic analysis within the subfamily Cecidomyiinae. The supertribe Stomatosematidi is a paraphyletic assemblage. Nearly all members of Lasiopteridi,Ozirhincus, Arnoldiola, BrachineuraandLedomyia, have a synapomorphic character in the great number of microtubules in parallel to the axoneme. A notable exception isRhizomyia, which shares certain apomorphic traits with several genera that have previously been classified within the Cecidomyiidi, i.e.Contarinia, Allocontarinia, LestodiplosisandMyricomyia.Moreover, these genera have a flat sperm tail and microtubular doublets located close to the cell membrane, both characteristics that differ markedly from the very peculiar sperm tail found in other members of Cecidomyiidi.Cladistic analysis of sperm characters suggests that the supertribe Cecidomyiidi is a polyphyletic taxon and supports the existence of a sister‐group relationship between the supertribe Lasiopteridi and the generaRhizomyia, Contarinia, Allocontarinia, LestodiplosisandM