insect-pollinated flowers use bright colours, patterns, rewards of nectar and pollen, and scent to attract pollinators such as bees. some also use drugs such as caffeine to encourage bees to return more often. advertising is influenced by sexual selection: in dioecious plants like sallow, the male flowers are brighter yellow (the colour of their pollen) and have more scent than female flowers. honey bees are more attracted by the brighter male flowers, but not by their scent.