This family of flies is distinguished by having only 1 pair of wings (Bees & Wasps having 2 pairs). The body colours mimmic those found on Bees and wasps although they are perfectly harmless to humans.
They are broken down to three sub-families: Syriphidae, Eristalinae and Microdontinae. This latter sub family is rare in in the UK.
They are seen hovering around flowers amongst butterflies and other insects and are an important polinator themselves.