Alien species might disrupt the mutualistic relationships between plants and animals. In the aspect of pollination, when co-occurring alien species with larger flower show extensive overlap in flowering phenology, they may compete for service of share pollinators. The reduction in pollinator visitation of native species results in a decrease in reproductive success. In Japan, the agamospermous hybrid between native dandelion (Taraxacum japonicum) and alien congener (Taraxacum officinale) became the stronger competitor for pollination to native one in the field. To better understand the reproductive interference, we observed the foraging bouts of honey bee (Apis mellifera) in mixed-species artificial arrays of natives to hybrids. Honey bee showed the relatively high-preference for hybrid dandelion, but variation in flower constancy. The bee foraging pattern suggests that the competition for pollinator between native and hybrid dandelion may be caused by both exploitation (hybrids draw pollinators away from natives) and interference (loss of pollen and stigmatic surface by interspecific pollination). Beside, the incomplete constancy probably lead to naturally occurring back-crossing hybrids in the field.