A pollinator is an animal that does pollination. Pollination is almost entirely done by insects, though there are some exceptions. Some birds (such as hummingbirds) pollinate flowers as they take nectar. Overall, however, it is insects that pollinate. Bees, of course, pollinate flowers as they take nectar. But wasps, ants, flies, beetles, butterflies and moths all have many species which are pollinators. The plant which offers the pollen is called the pollenizer.