Studies were conducted with Ugandan isolate of Coelomomyces stegomyiae against mosquito larvae. Aedes aegypti first instar larvae was most susceptible (99.8%) within 6 days, and the fourth instar was least susceptible (44.4%). Culex quinquefasciatus suffered 70% mortality within 10 days. Mortality rates were 92.5% for Culex tigripes, 70% for Culex duttoni, 89.5% for Aedes africanus, 89.9% for Anopheles gambiase and 97.3% for Aedes simpsoni. There was no infection when two species of the predatory mosquito Toxorhynchites were exposed to infection. A few adults emerging from an infected larval population were found infected when dissected. Other mosquitoes that pupated died and the pupae were found infected. Infected females were produced by 19.2% of the fresh pupae exposed. The importance of the results in biological control is discussed.
