A study of the phenology, breeding system and insect pollinators of D. lonicera demonstrated the flowers to be protogynous, self-incompatible, non-apomictic and adapted for pollination by bumble bees and hawkmoths. The style and filaments increased in length during anthesis. The stigmas were very receptive for up to 48 h after the start of anthesis. A color change in the corolla was linked with a decrease in flower visitation by bumble bees (Bombus vagans and B. terricola). Adults and larvae of the hawkmoth, Hemaris diffinis are associated with the plant in 4 widely separated localities. The flowers open late in the day, but no nocturnal pollinators were observed. Noctural hawkmoth pollination may occur in the southern part of the plant''s range.