Entomophagous Syrphidae feeding on grain aphids of Western Siberia can be infested by twenty species of Hymenoptera belonging to five families. The most abundant parasites are Promethes sulcator Grav., Diplazon laetatorius F., Syrphoctonus signatus Grav., Woldstedtius biguttatus Grav. (Ichneumonidae), Pachyneuron groenlandicum Holmgr. (Pteromalidae). Infection of Syrphidae by parasites during the period of the study fluctuated from 3,2 to 56,9%. The ratio of different parasites on the fields, the data on their biology and seasonal dynamics of the infestation of Syrphidae by parasitic Hymenoptera are given.