Dasineura gannoni Kolesik sp. nov. is the first gall midge species known to feed on plants from the Hakea-Grevillea generic alliance. D. gannoni induces galls on swamp-loving Hakea microcarpa R. Br. and H. nodosa R. Br., flowering plant shrubs naturally occurring in south-east mainland Australia and Tasmania. The gall is a conspicuous red-coloured, multi-chambered, leaf swelling containing one, occasionally two, red larvae in each chamber. Pupation takes place in the soil. The new species was originally identified on H. microcarpa near Thredbo River in New South Wales. Later examination of herbarium vouchers found presence of galls of the new species on further specimens of H. microcarpa and another swamp-loving species H. nodosa. The geographical range of the new species extends over much of the combined distribution area of the two host plants on mainland Australia from far south-east Queensland through east New South Wales to Victoria and south-east South Australia.