Culex nigripalpus Theobald, was maintained on different concentrations of sucrose solution to study sugar-feeding behavior and survival, and on 10% sucrose to study blood-feeding behavior, insemination and oviposition. The F1 females did not become inseminated and consequently did not oviposit. Sugar-intake during the first week was high at all concentrations, followed by an almost constant lower level daily intake during the next 4 weeks. This regulation of sucrose intake in females was associated with a build up of energy reserves. While male and female mean survival time varied from 2.6 to 3.1 days on distilled water, colonized males lived from 19.8 to 23.7 days colonized and F1 females from 37.5 to 53.4 days on the 3 sucrose concentrations. Insemination began 3 days after emergence with 100% insemination by day 9. Only a small percentage of females blood-fed without previously imbibing sugar solution. Insemination, however, was not a prerequisite for blood-feeding. Only a small percentage of blood-fed colonized and wild caught females oviposited, and oviposition was asynchronous, while repeated blood-feeding and oviposition reduced the mean survival time of colonized females.