Haemocoelic injections of live Escherichia coli and oral administration of three tetracycline compounds, namely Reverin, Maxitet and Terramycin to female Glossina morsilans morsitans prior to their first larviposition, caused a decrease in fecundity, but had no effect on longevity. Trypanosoma brucei brucei and T. congolense administered by haemocoelic injections, however, caused no change in fecundity or longevity, but tsetse infected with T. b. brucei and T. congolense in their mouthparts had decreased fecundity and longevity as compared to controls.