Few age-structured models of species dynamics incorporate variability and uncertainty in population processes. Motivated by laboratory data for an insect and its parasitoid, we investigate whether such assumptions are appropriate when considering the population dynamics of a single species and its interaction with a natural enemy. Specifically, we examine the effects of developmental variability and demographic stochasticity on different types of cyclic dynamics predicted by traditional models. We show that predictions based on the deterministic fixed-development approach are differentially sensitive to variability and noise in key life stages. In particular, we find that the demonstration of half-generation cycles in the single-species model and the multigeneration cycles in the host-parasitoid model are sensitive to the introduction of developmental variability and noise, whereas generation cycles are robust to the intrinsic variability and uncertainty that may be found in nature. Life cycle and development; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology Plodia interpunctella (Pyralidae); Life cycle and development; Hymenopteran parasites; Venturia canescens; Host-parasite interactions, significance of developmental variability & demographic stochasticity; Population dynamics Venturia canescens (Ichneumonidae); Life cycle and development; Lepidopteran hosts; Plodia interpunctella; Host-parasite interactions, significance of developmental variability & demographic stochasticity; Population dynamics none