Flowers of Lilium philadelphicum bear pollen mostly during the first day of bloom and nectar on an irregular schedule during the first six days of anthesis. Pollination experiments suggest that this species must cross-pollinate to produce seeds. Butterflies which transfer pollen of this lily with their wings and pollinating sweat bees show "suboptimal" foraging movements on individual flowers. Mirid bugs, ants, and other butterflies steal nectar. Tortricid larvae consume flower parts.