IV-Climate and tsetse flies: laboratory studies upon Glossina submorsitans and tachinoides

Abstract

Introduction —It is probably true that wild populations of Glossina have been more studied than populations of any other insect. Nearly all this work has been based on fly-counts, and it is beyond dispute that this method has given results of great value. But the fly-count is open to objection, for the number of flies caught is determined partly by the population (which we wish to measure), but also to an unknown extent by the activity of the insects at the time when the count is made. The effect of these two factors cannot at present be distinguished, and it is not likely that any improvement in the technique of the fly-count will enable the distinction to be made. All the conclusions that are based on fly-counts (and they are many and far reaching) are therefore to some extent speculative. It appears therefore that some entirely new way of studying the Glossina population is required. In this paper it is suggested that the effect of climate upon Glossina is capable of study and analysis in the laboratory. Let it be admitted that the conditions are artificial, also that the authors have limited themselves to temperature and humidity, whereas in nature there are many climatic factors which influence the fly. In answer it is claimed that the methods employed justify themselves, and that if they were more widely used our knowledge of these insects would soon rest on a more solid base.