The Ecology ofGlossina morsitans, Westw., and two possible Methods for its Destruction.—Part II

Abstract

A small belt of Glossina morsitans has been studied for four and a half consecutive years.The community has been observed during the period of its prosperity when the population increased and attempted to colonise unsuitable country ; the outward spread of the fly was checked by insuperable natural barriers, and a period intervened when the fly advance had come to a standstill ; the tsetse were observed in their attempt to breed and establish themselves in an area that could only temporarily suffice their needs.This optimum period was brought to a sudden close by the advent of unfavourable climatic conditions. The effort made by the community to establish a habitat in an unsuitable type of bush was frustrated by the almost complete extermination of its population. The country which had been colonised by the tsetse was depopulated, and once more was limited to a small population that had survived in the true and permanent habitats. A long period followed in which the tsetse were seen to make a slow but steady recovery. The investigation closes with recovery assured, but the community still too depleted in numbers to attempt further expansion for a considerable time.Throughout this rise and fall in the fortunes of the fly community, the size of the tsetse population has been seen to fluctuate seasonally with the annual variations in the climate.