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Please help. The fly from greenhouse with tomatoes, North Caucasus, February 2016.

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Head

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Scatella - Ephydridae. The same situation as with Sciaridae thread:) Too much wet decaying substartes. Stop watering greenhouse for several days to make the soil dry.

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Sometimes this effect may be result of phytophtora desease:|

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This one is Scatella tenuicosta. They feed on the algae that live on the damp soil, and while they do not damage the plants directly, they are implicated in the spread of various plant diseases. Could I have the location for this record, please?

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The species keys to Scatella stagnalis (after Nartshuk, 1970), because the wings bearing light spots, body black and costa not thinned. Is it right? Scatella stagnalis is a common species in greenhouses: http://www.ipm.illinois.edu/greenhouse/insects/shore_flies/index.html

Collection point - 44°01′25″ N 41°56′54″ E

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The thickness of the costa is variable in tenuicosta, although stagnalis is generally thicker. The shape of the apical white spot (with constricted middle) is right for tenuicosta. S.stagnalis has a rounded spot.
Although S.stagnalis is often recorded from greenhouses, I have looked at several thousand greenhouse Scatella, and never found stagnalis. In the Holarctic region, only tenuicosta and obscura are found in greenhouses. (paper in preparation).

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Thank you very much, Tony! Do you need more pictures to confirm the ID?

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No, I'm happy with the ID - but I'd like to include the record in my paper, so a location would be good (North Caucasus looks like a big place!) Thanks, Tony

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Russia: Karachay-Cherkessia,
v.Kubina, Agrokombinat Yuzhnyi
44°01′25″N/41°56′54″E
Greenhouse, tomato,1-11.ii.2016

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Thanks, Igor :)