Published online by Cambridge University Press: 10 July 2009
Glossina palpalis fuscipes Newst. was studied in lake-side forest in north-east Lake Victoria and in riverine forest on the Kuja river, which runs into Lake Victoria. Climatic records are given. Trees counts were made in fifty acres of lake-side forest.
Populations of G. palpalis exhibit long-term fluctuations which are not annual and not related to season. On the lake shore, the density of G. palpalis is roughly correlated with the width of the forest, being least where the forest is narrow. In a block 2,200 yeards along the shore by 100 yards wide (this was the widest forest studied) the population was 4,600 non-teneral males. The mean catch along the 2,200 yards of shore was 78 non-teneral males. Calculated on an area basis, this is more than ten times the population which would be inferred from the same catch of G. morsitans or G. swynnertoni. The mean death-rate in this isolated block was 26 per cent. per week, and the mean length of life was 27 days.
Analysis of catches indicates that riverine G. palpalis are always more hungry than those on the lake shore, for the percentages of tenerals, of females, and of males attacking, are all higher on the river. Catches from a boat produce more females but fewer males than land catches. Carrying a screen produced more females on some occasions, but not on others, the discrepancy being unexplained.