Prior to 1900–05 South Ankole was free from tsetse.About 1906–07 Glossina morsitans crossed the Kagera northwards at three points: Kakitumba, Nyaruambu, and Kafunza (Tanganyika). Cattle in those areas were moved north on the advent of the fly, thus spreading it in small numbers, mainly northwards.The epizootic recorded in Ngarama and Bukanga in 1910–11 was due to “direct” transmission following the introduction of infected cattle from the south.The influx of man in 1914–15 through the Nyaruambu and Kafunza centres, chiefly the former, caused marked disturbances and rapid spread of the fly, principally along the line of communication to the north.The sudden withdrawal of the human element resulted in marked diminution of fly density, and the advent of rinderpest in 1919 destroyed an important alternative food supply, thus giving further impetus to the reduction.After a period of 27 years the tsetse had retired to those two points from which it had originally spread.The Kakitumba centre had not suffered human invasion, as did the foregoing, and no great activity of Glossina has therefore been recorded.The picture presented is that man himself has proved the greatest factor in that wide and rapid spread of Glossina which Ankole experienced during 1907–1917.