(1) Female larvae of the pitcher-plant mosquito (Wyeomyia smithii Coquillett) were reared through the 3rd and 4th instars with either a generous or a limited quantity of food. (2) Food regimen influenced neither the average duration of the 3rd instar nor the variance about that average. (3) Mean duration of the 4th instar and variance about that mean increased significantly among underfed larvae. (4) Weight at pupation varied directly with duration of the 4th instar among underfed larvae. Among larvae fed well pupal weight was independent of duration of the 4th instar. (5) Mean age at first reproduction, alpha, increased among the underfed females. Prolongation of the 4th larval instar caused this postponement of alpha. (6) Average gross lifetime fertility, Rg, differed between the larval food regimens. (7) Rg did not vary with pupal weight. (8) Three analyses of phenotypic variation in pertinent demographic and life-history characteristics fail to demonstrate a cost associated with reproduction in W. smithii. The data indicate that nutrients accumulated in the 4th larval instar will be used only in oogenesis, virtually none for adult somatic maintenance. We speculate about the evolution of autogeny and physiological rigidity of nutrient allocation processes.