Syritta pipiens is a very common species of European hoverfly.
It is very small (length: 6-9 mm) and easy to overlook but the strange thickened rear legs make it easy to identify at close range.
They are fast nimble fliers that hover all the time.

It took a long time to sit down, which allowed me to get this shot!

In my yard, Hilversum, The Netherlands, 1 July 2013