Reliable methods to attract European corn borer, Ostrinia nubilalis (Hübner), adults to small grain crops could be used to aggregate moths into small well-defined areas for control purposes or could be used in a resistance management program for delaying potential O. nubilalis resistance to transgenic corn. The objective of this research was to determine whether small-grain crops could be managed to influence O. nubilalis aggregation behavior. In farmer-managed oat, Atena sativa (L.), fields, more O. nubilalis adults were attracted to high-density patches of oat compared with standard patches of oat; no difference was found between patches of high-density oat and brome, Bromus spp. Numbers of O. nubilalis moths found in 6 barley, Hordeum vulgare (L.), and legume treatments (1995), and 4 oat/legume treatments (1996) were significantly different. The highest number of O. nubilalis adults were observed in barley planted with alfalfa, Medicago sativa (L.), followed by barley planted with crimson clover, Trifolium incarnatum(L.), barley planted with berseem, Trifolium alexandrinum (L.), barley planted with black medic, Medicago lupulina (L.), barley alone, and barley planted with lespedeza, Lespedeza stipulacea (Maximowicz). Double-planted oat attracted the highest number of O. nubilalis adults followed by oat planted with crimson clover, oat planted with alfalfa, and single-planted oat. Each study suggests that there is a positive correlation between moth aggregation and canopy area. Suggestions are made that timing canopy closure of a small-grain crop with peak O. nubilalis flight should maximize O. nubilalis aggregation and should thereby increase the efficacy of any control measures.