Hoverflies are the best known wasp and bee mimics, which do an impressive impersonation of their more dangerous distant cousins.
Many hoverflies have evolved these black and yellow ‘don’t mess with me’ markings, but are just bluffing – they are completely harmless.
As in most other hoverflies, males can be easily identified by their holoptic eyes (eyes touching at the top of their heads).
Females usually have smaller eyes, which are further apart (dichoptic eyes).

A female. 's Graveland, The Netherlands, 12 August 2011