Melanostoma dubium is a Palearctic species of hoverfly.

[4][5] Found from Fennoscandia south to the Pyrenees and from Scotland east through North Europe and the mountains Central Europe into European Russia and on through Siberia to Yakutia.

The habitat is montane and alpine grassland and moor.

Flowers visited include Carex, Potentilla erecta, Ranunculus.

Flies from July to August dependent on altitude.