In some mosquito species the conditions experienced by larvae during development have been shown to lead to changes in susceptibility to various arboviruses in the adult female. Since laboratory mosquitoes are generally reared under ideal conditions, mosquito vector competence experiments in the laboratory may not accurately reflect vector?virus relationships in nature. We examined the consequences of larval nutritional stress on Culex tarsalis vector competence for West Nile virus (WNV). Larval nutrition deprivation resulted in increased development time, decreased pupation and emergence rates, and smaller adult female body size. However, infection, dissemination, and transmission rates for WNV at 5, 7, and 14 days postfeeding were not consistently affected. These results suggest that larval nutritional rearing protocols are not a major factor in laboratory estimates of WNV vector competence in Cx. tarsalis.