Abstract: The use of supplemental lighting in greenhouses under short-season conditions is well recognized to improve crop yield and quality. However, artificial light sources may also alter the establishment and reproductive potential of pests and biological control agents. In this study, a trial was performed on tomato crops under short-season commercial greenhouse conditions to compare how three different LED and one HPS supplemental lighting regimens might affect the establishment of generalist predator Dicyphus hesperus (Knight). Beginning on February 26th 2016, fourth instar D. hesperus predators were introduced into clear plastic leaf cages on the crop and were subsequently monitored on a weekly basis for survival and reproductive output. The use of supplemental lighting in this trial extended the natural light photoperiod from 11 hours and 3 minutes at the start of the trial to approximately 16 hours a day. Overall, supplemental lighting conditions improved predator survival by 30-35% relative to unlit control conditions. Furthermore, a greater total number of offspring nymphs emerged from leaves held under lit relative to unlit conditions indicating that light supplementation can directly impact the reproductive output of Dicyphus hesperus predators. In this trial, photoperiod is more important to the establishment of this generalist predator than is light quality, as no differences were observed between the various supplemental light treatments. These results highlight the potential of supplemental lighting to translate to improved short-season greenhouse crop protection.