This is a couple of marsh flies also called snail killing flies (Elgiva solicita). In Germany they are called Hornfliegen (horn flies, because of their large antennae). They are my favorite flies as almost all members of this family (Sciomyzidae) own beautiful striped eyes and they are very relaxed little fellows (not like the stressful flies in houses).
This pic shows Dioctria atricapilla. In Germany it is called Black Robber Fly, but I did'nt find an english name for it.
When I took this photo the sun had just disappeared beyond the horizon and so exposure time was very long (5 sec). One out of approx. 15 pics was sharp the others were blurred due to a moderate breeze.