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Well, in this case I agree with Maja, and I think this is a female of Chrysotoxun intermedium!
The third antennal segment is clearly longer than segment 1 and 2 together, abdominal hairs (seemingly) very short and frons yellow!
Also size and color of abdomen are different from cautum.
This is how a typical female cautum looks like:
http://www.microscopy-uk.org.uk/mag/imgmay07/chrysotoxum_cautum.jpg

The membranous strip on segment 6 I'm talking about is visible on this specimen:
http://www.evasion.it/ditteri/Chrysotoxum_cautum00.jpg
Between the more orange colored parts of tergite 6 one can see the membranous strip as a yellow line in the middle!
That's a feature only the female of cautum has!!
Greetings,