About 90 taxonomically described and undescribed species are recognized in the genus Colocasiomyia of the family Drosophilidae, Diptera, mainly from the Oriental and Papuan (Australian) regions. Colocasiomyia flies visit flowers of the families Araceae, Arecaceae and Magnoliaceae, showing various levels of host specificity. Several intimate pollination mutualisms are confirmed where the flies utilise inflorescences as their brood sites. In this symposium, we review the biogeography, ecology and phylogeny of the pollination mutualism between Colocasiomyia flies and Araceae plants, emphasizing recent new records of the flies in their northern limits in Kyushu, Shikoku and Honshu.