Sunflower moth (Homoeosoma electellum Hulst (Lepidoptera: Pyralidae)) is a native pest of sunflower (Helianthus annuus L.) in California. The parasitoid guild of H. electellum is comprised of a variety of native and introduced parasitoids that attack the larvae in the “wild” (self seeding) sunflower habitats and in domesticated (agricultural) sunflower fields. We examined the composition of this parasitoid guild in the Great Central Valley of California using three different approaches to address the questions: 1) Does surrounding landscape composition affect the species richness, ratio of specialists to generalists and overall parasitism rates in wild and agricultural sunflower habitats? 2) Does the specialist parasitoid of sunflower moth, Dolichogenidea homoeosoma Muesbeck (Hymenoptera: Braconidae), exhibit genetic population structure at the habitat (wild vs. ag) or geographic scales? And 3) Does flowering phenology in agricultural sunflower fields exclude parasitoids of H. electellum? We found: 1) surrounding landscape impacts the parasitoid guild composition factors of species richness and ratio of specialists to generalists but not the overall parasitism rates (p=0.049). 2) The specialist D. homoeosomae, does not exhibit genetic population structure based on habitat type, but does exhibit some structure at the broader geographic level. 3) Temporal exclusion of parasitoids of H. electellum, may limit the species richness and overall parasitism rates in agricultural fields. This study demonstrates how the use of landscape genetics, landscape level surveys and sentinel experiments together improve our understanding of parasitoid communities and their effectiveness in biological control of pest species.