Abstract: Pollination systems that rely equally on several different functional groups of pollinators are generalized whereas pollination systems that rely primarily on one functional group of pollinators are specialized. Flowers that are open during the day and the night can be generalized by being pollinated by distinct groups of pollinators during the day and the night. Silene stellata (Caryophyllaceae) appears to have this sort of generalized pollination system. S. stellata is visited by bees during the day and moths at night. A recent study shows that both day and night pollinators can elicit equal female reproductive success (Richards, unpub. data). However, the effects of day and night pollinators on the male reproductive success of S. stellata have not been previously investigated. This study quantified the relative importance of day and night pollinators to the male reproductive success of S. stellata. Fluorescent dye served as an analog of pollen to track pollen movement in the field. Moths elicited significantly more inter-plant dye movements than bees. The frequency of night dye movements was approximately three times the frequency of day movements. The mean day and night dye movement distances did not significantly differ. This studies reveals that S. Stellata has a degree of specialization to moth pollination through its male reproductive success. Since moths elicit more male reproductive success than bees, moth mediated selective pressures are potentially more important to S. stellata floral trait evolution.