The genus Ethmia is a megadiverse microlepidopteran group comprising more than 300 species worldwide. Currently 47 species-groups are proposed for the Palaeartic, Nearctic and Indo-Australian Ethmia species, respectively, but many more from the Afrotropical region are not assigned to any species group. Their hostplant associations involve at least seven ansgiosperm families, of which Boraginaceae is utilized by the majority of the species. The monophyly of this genus and assumption of evolution of host associations, however, were never tested using modern methods. We selected 52 Ethmia species having Hostplant records to represent 21 of the 47 species-groups and used Orophia (family association uncertain), Depressaria, Agonoterix, Chrysethmia and Agrioceros as the outgroups. Seventy six morphological characters were identified and the characters were partitioned into two subsets, non-colour patterns versus colour pattern to detect the impact of colour pattern characters on the phylogenetic structure. We employed maximum parsimony method to reconstruct the phylogenetic relationship of the Ethmia sampled and found that neither the genus Ethmia nor most species-groups proposed by previous authors are monophyletic. The characters relevant to colour patterns produced significant effect on the tree topology although the wing patterns may not be involved in mimicry. Optimalization of host associations reveals that the clades using Hydrophylaceae, Rosaceae, Phytolaccaceae, Scrophulariaceae, Ranunculaceae and Malvaceae have evolved independently from the clade using Boraginaceae.