The classical image of an insect pollinator is a bee or a butterfly. This is probably because bees are not only common but they are among the few insects that have been managed by man for food and pollination, and in the case of butterflies because they are easily recognizable insects and are often brightly colored.
There are, however, many different kinds of insect pollinators which include different bee species, some of which are social and some solitary. Solitary bees do not form colonies, but live rather independent lives. Each female solitary bee will fetch products to build a small nest and feed her young, one at a time. In Hawaii, we have a number of native bees species called Yellow Faced Bees that are solitary and some introduced species, such as leaf cutter bees, which are also solitary.
Yellow faced bees collecting pollen on a flower, yellow face bees have strong preferences for native plants.
Some species of leaf cutter bees will use small bits of leaves to create a cylindrical nest for their offspring. Leaf cutter females have long hairs on the underside of their abdomen where they pack pollen to take to their young.
Some bees are very small and not fuzzy, which makes them look more like wasps, which also visit flowers to drink nectar and look for insect prey.

An example of these kinds of bees is the small carpenter bee, which often nests inside stems or dead twigs.
Wasps are also common plant visitors, and some actually function as effective pollinators. In some Hawaiian islands such as Molokai, flower wasps are relatively common. These wasps are actually hairy and can help transport pollen between flowers.
Flies are often considered unsanitary pests, but many fly species, prefer to feed on flower nectar and are active pollinators of tropical fruit trees. Hover flies are among the most common flower visitors in urban and agricultural systems in Hawaii. Some of these species are quite large and some are striped, looking more like wasps than flies.
Hover flies are not the only ones to visit flowers, midges, tachinids, and blow flies, also contribute to pollination of common crops.