Gyrostigma rhinocerontis (also known as the Rhinoceros stomach botfly) is the largest fly species known in Africa. It is a parasite of the Black Rhinoceros and the White Rhinoceros. Because the fly depends on the rhinoceros for reproduction, its numbers declined steeply as the black and white rhinos faced extinction. Like the rhinoceros, it must once have spread across much of sub-Saharan Africa (outside of the Congo Basin), but is today restricted to the savanas of southern and eastern Africa.