The use of imidacloprid for the control of green peach aphid, Myzus persicae (Hemiptera: Aphididae) on greenhouse pepper has become widespread in British Columbia, Canada. Growers often apply imidacloprid systemically to mature pepper plants following aphid outbreaks. This study was undertaken to examine the toxicity and persistence of a systemic imidacloprid treatment at different heights of the pepper canopy. Aphids were placed on leaves in clip-cages at three different locations (top third, middle, bottom third) on mature pepper plants. Aphid mortality and reproduction were then assessed 0, 2, and 4 weeks post-treatment and the week immediately prior to the treatment. Preceding the insecticide application, aphid mortality did not differ among leaves at different heights, whereas aphid reproduction was lowest in clip-cages placed at the top height. The week following the imidacloprid application, aphid mortality and reproduction did not differ among the plant heights. At two and four weeks post-treatment, aphid mortality was lower, and subsequently aphid reproduction was higher, in clip-cages placed on top leaves than in cages placed in the middle or bottom of the canopy. Implications of the results to aphid movement, pest monitoring and insecticide resistance management are discussed.