The relationship between axil age and water-holding capacity on the presence and age of immatures of Aedes (Stegomyia) simpsoni (Theobald) complex (Diptera: Culicidae) in cultivated banana, Musa spp. (Musaceae), Colocasia esculenta and Xanthosoma sagittifolium (Araceae) during the rainy and dry seasons at different locations in Uganda is presented. On Masa spp., higher, younger axils were found to contain more water than older Ones. In some seasons these axils held more immatures of Aedes simpsoni complex than the lower, older axils of the plant. On C. esculenta and X. sagittifolium plants, the middle and lower axils held more water, and had a greater abundance of larvae and pupae. There were generally no significant differences (P > 0.05) in the mean age of larvae and pupae found in axils of different ages.

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.