ABSTRACTFourth instar larvae ofAedes aegypti, lightly infected withCoelomomyces stegomyiaewent on to pupate and produce adult mosquitoes which carried the fungal infection. Adult behavior related to taking of blood meals, copulation and oviposition were not affected by infection. The reproductive organs of adult male mosquitoes were not directly affected by the fungus but, following blood meals, the ovaries of females became filled with fungal resting sporangia and no eggs were produced. When infected females attempted to oviposit eggs, they instead oviposited small piles of resting sporangia. Zoospores from oviposited resting sporangia infected the harpacticoid copepodPhyllognathopus viguieriwith the gametophytic stage of the fungus.