We evaluated responses of plum curculio, Conotrachelus nenuphar (Herbst), to baited and unbaited black pyramid and Plexiglas panel traps in mark-release-recapture experiments to determine whether presence of host apple trees diminishes trap effectiveness. Identical experiments were conducted in an open field (little competition present) and in an unsprayed apple orchard (presence of competition from natural host apple trees). Results of mark-release-recapture experiments were successful; we recaptured 21.0 and 2.9% in the field and orchard, respectively. Plum curculio response to traps was influenced by presence of apple trees, because significantly more recaptures were recorded in the field compared with the orchard. Pyramid traps recaptured more plum curculio in the field compared with the orchard and recaptured significantly more plum curculio compared with panel traps. Female plum curculio responded in significantly greater numbers to pyramid traps baited with benzaldehyde compared with unbaited traps in the field, but not under orchard deployment. Combined data indicate that positioning traps in proximity to host apple trees diminishes both trap and bait effectiveness either by direct competition from host tree stimuli or by physical obstruction of trap-related visual stimuli and/or volatile release. We conclude that an effective trap-based monitoring system for plum curculio will require better odor baits, trapping mechanisms, and/or deployment strategies that can overcome visual and olfactory interference presented by host apple trees.