Pollination[edit]
While the vast majority of wasps play no role in pollination, a few species can effectively transport pollen and therefore contribute for the pollination of several plant species, being potential or even efficient pollinators;[4] in a few cases such as figs pollinated by fig wasps, they are the only pollinators, and thus they are crucial to the survival of their host plants.
Source: Wikipedia
I didn't get a chance to ask the wasp what kind it was, an effective pollinator or not. I was surprised to see it stay with the plant going from flower to flower. There are more buds on the tree that I suppose will open into more flowers. I will be amazed if that dwarf tree actually grows a Mandarin orange. It's possible that was a bee and not a wasp but I haven't been aware there are bees out there.
There are a zillion small and large bees and wasps in front of the house on Azalea bushes on both sides of my front door. There are tons of flowers on those large mature bushes.