Abstract
The habits and habitations of the natives in the Bwamba lowlands, Uganda, are briefly described. A series of catches designed to assess the relative importance of the various species of biting insect and of various routes of transference in the transmission of yellow fever virus from the monkey population of the forest to the nearby human population is reported. The microclimate in a native hut is discussed. The species of biting insect encountered are listed, the results of the catches given, and the relative importance of the different species and routes assessed by means of indices. It is concluded that yellow fever virus is most likely to be transferred to the native population by A. (S.) simpsoni in plantations, the infection in this insect being derived from forest monkeys which raid the plantations for food.