§ Mr. Dodds-Parkerasked the Secretary of State for the Colonies what progress is being made and by what means, in the experimental elimination of the tsetse fly in the various East African Colonies; whether any success has been obtained from aerial spraying; and whether spraying from a slow-moving helicopter has been considered.
§ Mr. George HallExperimental work on the elimination of the tsetse fly in East Africa has been in progress since 1927 in Tanganyika, where a Tsetse Research Department is in being. The main activities of the department have been devoted to research into the technique of clearing areas of tsetse fly both by entomological means and by reclamation, from "sheer clearing," i.e., the removal of all trees and shrubs from the affected area to "discriminative clearing" which consists in cutting out only those parts of the bush which provide the fly's permanent home. Methods vary according to the type of vegetation and the species of fly encountered. Experiments are continuing and in the past 10 years, in Tanganyika alone, 1,150 square miles of land have been cleared and 45,300 persons re-settled on the land. An additional 1,130 square miles is in course of reclamation and further areas are being surveyed. As a result of the knowledge gained in Tanganyika, similar methods of reclamation have been adopted in other East African territories. It must, however, be emphasised that in all cases it is absolutely essential that the areas which have been reclaimed should be re-settled by human population in order to hold what has been won back. Other experiments include the elimination of tsetse by the removal of game, in a small area of Tanganyika, and research into the use of insecticides, particularly D.D.T. and I.C.I.666, by a Colonial Insecticide Research Unit. The main problem here is the application and dissemination of the insecticide, and research is to be undertaken in this country on suitable apparatus 181W for this purpose. Field trials will be arranged as apparatus comes forward for testing. Further investigation is required into the question of the absorption of insecticides by vegetation. Experiments with repellents are also under consideration. Experiments with spraying from aircraft have been carried out mainly in South Africa. Results so far are encouraging, but further research is necessary on the residual effects of D.D.T. on insects generally, and the consequent effects on the "balance of nature." This is a wide problem which is now under consideration. The use of helicopters has also been considered, but there are technical difficulties connected with the altitude at which the aircraft are required to operate Further experiments are, however, projected both in South and East Africa as soon as the prototype of a suitable machine can be obtained.