The earliest known cases of the coincident disappearance of tsetse-fly from an area affected with rinderpest occurred in the Transvaal and Rhodesia in the early nineties of last century (Stevenson Hamilton, 1911 and 1912). There is no doubt that the fly either decreased or entirely disappeared from various districts in these two territories following the great rinderpest epizootic in the wild fauna. A satisfactory explanation has not yet been given to account for this remarkable phenomenon.

Fuller (1923) in a most interesting historical review of the tsetse position in the Transvaal and neighbouring territories points out that although there had been a gradual shrinkage of the fly over a period of some years, the disappearance of Glossina from the Eastern low country of the Transvaal can be definitely attributed to the rinderpest epizootic. He further states (p. 347) that “ it has been shown experimentally that disease-laden blood does not militate immediately against the fly.” No reference is given in support of this statement, and I am unable to trace any published experimental evidence in this connection, with the exception of Duke's (1919) work, which is referred to later.

Howard (1910), discussing the tsetse position in the Inhambane and Lourenço Marques districts of Portuguese Territory, states that after rinderpest passed over South Africa the fly began to disappear and that they had been unable to locate a single tsetse-belt in that portion of the country.