Laboratory studies investigated the effects of weeds associated with reduced tillage in corn on a major black cutworm parasitoid, M. rubens. Adult female wasps provided with any of five flowering weed species lived longer, attacked more hosts, and produced more offspring than those lacking a food source. In addition, wasps maintained on a combination of three weed species in flower lived longer than those given nonflowering plants of the same species or no food source. These results demonstrate that flowering weeds associated with reduced tillage in corn are beneficial to M. rubens as nectar sources.