The main objective of the present study is to describe and compare the morphology of the female genitalia within a selected number of species and families of the lower Diptera. The results are presented as two papers with a common introduction. The first paper investigatesthe differences at the family level, based on four species representing the three families Tipulidae, Trichoceridae and Ptychopteridae. The second paper focuses on differences between species within one genus in the family Mycetophilidae. Females of four species in the genus Allodia Winnertz, 1863 were selected for this part of the study. The females are associated with already identified males through DNA barcoding. The common introduction gives a short review of the phylogeny of the studied taxa, the outline of female genitalia in lower Diptera and of DNA barcoding as a method for associating sexes.