Coccinella septempunctata; Coleomegilla maculata; Chrysoperla carnea; CONTROL-OF; SAMPLING-; Natural enemies of lepidopteran pests; INSECT-PREY; Ostrinia nubilalis (Lepidoptera); Natural enemy sampling, control implications; CULTIVATED-LAND-HABITAT; IOWA-; Story County; Natural enemies of Lepidoptera; Adjacent habitat & trap location effects, cornfields Ostrinia nubilalis; CONTROL-BY; Coleoptera, Hymenoptera & Neuroptera; FOOD-PLANTS; Corn; HYMENOPTERAN-PARASITES; Macrocentrus grandii; INSECT-PREDATORS; Chrysoperla (Neuroptera) & Coccinellidae (Coleoptera); CULTIVATED-LAND-HABITAT; IOWA-; Story County; Natural enemy sampling; Adjacent habitat & trap location effects, control implications, cornfields Macrocentrus grandii; CONTROL-OF; Ostrinia nubilalis (Lepidoptera); SAMPLING-; Natural enemies of lepidopteran pests; LEPIDOPTERAN-HOSTS; Ostrinia nubilalis; Natural enemy sampling, control implications; CULTIVATED-LAND-HABITAT; IOWA-; Story County; Natural enemies of Lepidoptera; Adjacent habitat & trap location effects, cornfields The influence of adjacent habitats, trap location, and trap height on capture numbers of predators and a parasitoid were monitored in Iowa cornfields using insect traps (Gempler's, AM No-Bait). Traps were fastened to a single wood lathe (122 by 3.8 by 1.3 cm) with wire ties at and 1 m above ground level. Traps at the 2 heights were placed in corn and their adjacent habitat. The adjacent habitat consisted of 1 of 3 types--herbaceous, wooded, and intermediate. Adjacent habitat did not significantly influence the number of Macrocentrus grandii Goidanich (Hymenoptera: Braconidae) captured but did influence the capture of Coleomegila maculata (De Geer) (Coleoptera: Coccinellidae), Coccinella septempunctata L. (Coleoptera: Coccinellidae), and Chrysoperla carnea Stephens (Neuroptera: Chrysopidae) with increased captures from fields with the herbaceous and intermediate habitats. Distance that traps were placed in corn and trap height significantly influenced numbers of M. grandii and C. maculata captured. Significantly more M. grandii and C. maculata were captured from traps 11 m into corn than from traps 2.5 m into corn or in the adjacent habitat. Capture rates of M. grandii also were significantly higher on traps 1 m above ground. Data from this research indicate that M. grandii is synchronized with its host, Ostrinia nubilalis (Hubner), in central Iowa.