Abstract: The present paper reports the development of Coelomomyces indica in Culex tritaeniorhynchus larvae.Experimental observations indicated that the first instar of the mosquito larvae can be infected with fungus.The hyphal bodies developed and produced sporangia in the haemocoele of the mosquito larvae.The sporangia were released in water from the dead mosquito larvae.The development of mature sporangia with zoospores was in water at 34℃ within 8 12 hours.The zoospores released from the mature sporangia within 1/2 1 hour under optimal conditions were very active in water and their activities decreased after 1 hour.The zoospores act as the infective stage for the Cyclops (host).