Mutualism in the garden.

A mutualistic relationship is when two organisms of different species "work together," each benefiting from the relationship. In this case the insect gets pollen and possibly nectar for food and the flower gets cross-fertilised with pollen from a previously visited flower.
I could suggest that it is a bit like a major donor to the Tory party receiving an unelected seat in the House of Lords, but that might be uncharitable!