Austrosimulium is a genus of about 30 species of black flies that are distributed in Australia and New Zealand.

There are 2 subgenera: Austrosimulium whose species are principally from New Zealand, and Novaustrosimulium which are exclusively Australian.

[2] Austrosimulium is a sister genus to the monospecific Paraustrosimulium of South America.

[3] Some species are known to spread the protozoan blood parasite Leucocytozoon tawaki in penguins.

[4][5][6] In New Zealand, where they are known as sandflies or namu (in Māori from Proto-Austronesian *ñamuk "mosquito", compare with Malay: nyamuk),[7][8] three species – A. australense, A. tillyardianum and A. ungulatum – bite humans.