The ability of Bracon hebetor Say, a larval parasitoid of certain stored product moths, to suppress a Plodia interpunctella (Hubner) population was studied in differing rice products. The larvae of P. interpunctella gathered on the topmost layer of the experiment cages filled with rice product (less than 3 cm in depth), and were rarely observed in deeper depths (deeper than 3 cm). Without P. interpunctella, A heetor did not show a preference for any of the three types of milled rice products used. In rice flour, the searching behavior of B. hebetor for P. interpunctella was limited, apparently due to the thick webbing prouced by the moth larvae. B. hebetor suppressed P. interpunctella population successfully in cracked rice kernels, but failed to suppress the moth population in rice flour. In whole rice kernels, B. hebetor suppressed the moth population only when the volume of rice in the cage was large enough to support a high population density of P. interpunctella (2.4! kg/cage). Success and failure of B. hebetor to suppress the moth population in the three different rice products are discussed in relation to the larval webbing and intraspecific cometition of P. interpunctella larvae. BR Animals and man. Control. Biological control. Parasites diseases and disorders. Parasites. Insect parasites. Hosts. Insect hosts. Ecology. Population dynamics. Habitat. Man made habitat. Plodia interpunctella (Pyralidae): Host; Bracon hebetor (Braconidae): Parasite. Bracon hebetor: Control of, Plodia interpunctella (Lepidoptera), Lepidopteran hosts, Plodia interpunctella, Host population suppression in stored rice, effects of milling degree and storage volume; Plodia interpunctella: Control by, Bracon hebetor (Hymenoptera), Hymenopteran parasites, Bracon hebetor, Population suppression by parasite in stored rice, effects of milling degree and storage volume, Population size, Stored product habitat, Stored rice. ST Insecta, Lepidoptera, Glossata, Heteroneura, Pyraloidea, Pyralidae; Insecta, Hymenoptera, Apocrita, Terebrantia, Ichneumonoidea, Braconidae. Arthropods; Hymenopterans; Insects; Invertebrates; Lepidopterans. none