What are the distinguishing features between Syrphus and Metasyrphus?

The official character will not make you very happy: The only genus in the Syrphini that has long hairs on the lower lobe of the calypter is Syrphus and that is used to separate the genus from all related genera. Fat chance that you will be able to see that on your pictures. :(

Another feature you will find in most Syrphus (but not in all and also in some species in other genera) is a dull mesonotum. Many Syrphinae have a strongly shining mesonotum, sometimes with two whitish stripes near the anterior margin. When you look carefully you can sometimes discern very vague stripes in some other species.

A character of Eupeodes (the proper name of Metasyrphus) not found in Syrphus is the margined abdomen. A second character (but be more careful with this one) is that Eupeodes has paired spots on the tergites that may merge to form bands. And that is where you have to be careful. In European species of Eupeodes it is allways clear that bands are narrower in the middle and thus consist of two confluent markings. I do not know if this is also the case in Nearctic species.

Anyway, this specimen has a dull mesonotum and bands on the tergites that do not appear to be narrowed. My conslusion: Probably Syrphus.

Paul

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