Forum Entomologi Italiani

Books consulted
Séguy 1961 : Diptères Syrphidés de l' Europe occidentale , Mémoires du MNHN
van Veen 2004 : Hoverflies of Northwest Europe - Identification keys to the Syrphidae , (1st Ed.)
Verlinden 1994 : Faune de Belgique - Syrphidés (Syrphidae) , IRNSB
Vockeroth 1992 : The Insects and Arachnids of Canada - part. 18, ... Syrphinae ...

http://www.esc-sec.ca/aafcmonographs/in ... art_18.pdf

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Astonishingly this ♀ has a abdomen cylindrical of ♂ !

I photographed the distinctive characters of the species ♀ :
- Shape of the yellow spots on tergites (But it is sometimes little obvious to differentiate scalare & mellinum).
- Antennae hairy (bare for mellinum), magnification X40.
- Profile of the head (significant character for Syrphidae).
- Face showing 2 pruinosity spots, above the basis of the antennae, wide and triangular (small for mellinum), but this criterion is not maybe relevant.