The Causes and Implications of Hunger in Tsetse-flies

Abstract

1. Tsetse-flies have been divided into four stages of hunger by their external appearance. These stages have been correlated with the internal appearance determined by dissection. It was found that the fat-bodies became maximally developed shortly after a meal, and thereafter diminished rapidly in bulk. Hunger of flies in samples is expressed as the Mean Hunger Stage (M.H.S.).2. Flies in different stages of hunger showed different behaviour in the field. Thus hungry flies usually attacked head-upwards, replete flies, if attacking, tending to adopt a head-down attitude. Most replete flies preferred to settle on the ground, or on objects other than the members of the catching party. Hungry flies were the most persistent followers.3. The true habitats and feeding-grounds of Glossina morsitans, G. swynnertoni, and G. palpalis are described, so far as they are known to the writer.4. Confirmation of the feeding-ground theory was obtained for G. swynnertoni by an analysis of the to-and-fro movements of marked flies.5. Considerable independent movement of flies was shown to occur in the absence of carriage on man or game. Some flies under such conditions travelled over 2 miles in 3 hours.