In the Spring of 2004, an agronomist (J. Singer) approached several entomologists (R. Hellmich, M. O’Neal, J. Prasifka, and N. Schmidt) about a collaboration to study the pest management benefits of incorporating living mulches in annual crop (corn and soybean) production. Living mulches are cover crops retained during the production of a main crop on the same parcel of land. A living ground cover can provide several benefits, including weed suppression, nutrient recycling, and reduced erosion (Hartwig and Ammon 2002). When compared with conventional production methods, a legume living mulch can fix enough nitrogen to reduce fertilizer requirements and increase yields in the main crop (Ilnicki and Enache 1992). However, living mulches may need to be suppressed to reduce competition with the main crop when water and nutrients are scarce (Echtenkamp and Moomaw 1989, Tharp and Kells 2001, Affeldt et al. 2004). Because living mulches reduce agricultural disturbances and increase vegetational diversity, changes in the community structure of arthropod pests and their natural enemies are likely (Andow 1991). Pest populations, particularly of aphids and lepidopterans, are often reduced by the adding living mulches to an agroecosystem (Costello and Altieri 1995, Vidal 1997, Hooks and Johnson 2004).