In the laboratory, 8.5% and 5.1% of colonized Culex annulirostris from Brisbane and Mildura, Australia respectively were autogenous when reared and maintained on nutrient rich diets. Females reared and/or maintained on poor diets mainly had ovaries at Christophers' stage I and exhibited from 0 to 0.7% autogeny. All autogenous females had previously mated. Insemination rates in the Brisbane and Mildura colonies respectively, were 72.8% and 78.8%. No autogeny was detected in 997 females reared from 7 localities throughout Queensland but this may have been due to their poorer nutritional status (as indicated by wing size) or more likely to a low insemination rate of 0 to 16%. Our laboratory results, particularly with well-fed females, may have little relevance to the field situation, where adults are generally smaller and less well-nourished.