The algaeNitzschia latensHustedt,Ctenocladus circinnatusBorzi, and two species ofOscillatoriawere isolated from Mono Lake, which is near Lee Vining, CA, and used to produce cultures containing only one algal species (unialgal cultures). Survival to pupation and rates of larval growth and development were compared among larvae ofEphydra hiansSay, which were reared on one of these algal species or on a diet prepared using the fish food Tetramin. It was found that larvae could be reared from the second larval molt to pupation when fed on a single species of algae. Larvae reared onNitzschiashowed significantly increased weight gain and survival compared with larvae reared onCtenocladus.Growth performance was always orderedNitzschia, Oscillatoria, thenCtenocladus.Larvae reared onNitzschiaorOscillatoriadeveloped significantly faster than those reared on Tetramin. The results indicate that single species ofNitzschiaandOscilatoriaare adequate food sources forE. hiansgrowth. Although larvae of this fly appear to be generalist algal herbivores, food quality varies between algal species.