Bee
Flowers were pollinated by insects such as beetles long before bees first appeared. Bees are different because they are specialized as pollination agents. Their body and behaviour  make pollination easier. Bees are generally better at the task than other pollinating insects such as beetles, flies, butterflies and pollen wasps. The appearance of such floral specialists is believed to have driven the adaptive radiation of the angiosperms, and, in turn, the bees themselves.