I study the taxonomy and phylogeny of the fruitfly (Tephritidae) genera Acanthiophilus and Tephritomyia, which develop in flowerheads of plants in the tribe Cardueae (Asteraceae). My focus is mainly on classic taxonomy and morphology-based cladistics, but I also employ molecular methods for a thorough phylogenetic analysis of the genera within the ‘Tephritis group’. I have also studied the flies’ life history and behavior both in Israel and Africa, and have so far discovered numerous new host associations and provided the first description of larval stages in this group. In my work I try to elucidate the complex associations between the flies and their host plants, in particular certain discrepancies between their respective zoogeographical distributions.