Hi all,
I pictured this female in Belgium around Huy on 2020-05-04.
It seems to be Platycheirus !
ObsIdentify we use in Belgium tells me it is P. albimanus but looking at the keys I read that in the P. albimanus group, if the 3d antenna's segment is orange below, it's Platycheirus sticticus
Here are some pictures I uploaded :
It is a female of the scutatus-group, since the hind femur is yellow with dark ring. Females of this group of three species can not be distinguished so far. P. albimanus har much more dark hind femurs, only yellow at the tips.