Most research examining mosquito larval nutrition has focused on fungi, bacteria, and particulate organic matter. Fungi and bacteria, however, may be nutritionally insufficient to support larval growth. We predicted that the presence of protozoans would have a positive additive effect on larval growth and survival compared with when they were absent. We conducted a laboratory experiment where larval performance (Experiment 1) of two species of container mosquitoes [Culex coronator (Dyar and Knab), Aedes albopictus (Skuse)] was compared under two food environments (bacteria and bacteria with protozoans, each with an artificial diet). We also conducted a laboratory experiment where larval survival (Experiment 2) of three species [C. coronator, Culex quinquefasciatus (Say), and A. albopictus) was compared between the same two food environments without the addition of the artificial diet. In Experiment 1, survival was significantly different between species, with no significant difference between food treatments. Specifically, A. albopictus exhibited significantly higher survival compared with C. coronator, regardless of treatment. There were no significant differences in male or female mass and the development time between each treatment for either species. For Experiment 2, there was a significant difference between species, but no difference between treatment levels. Again, A. albopictus had higher survival compared with C. coronator and C. quinquefasciatus. We found little evidence of a unique nutritional role of protozoans for mosquitoes in either experiment, although it remains to be seen if protozoans may help mosquitoes meet specific requirements not examined in the general life history traits we measured.