This medium-sized bee has a shiny black body with white hair bands on the apical tergites, two submarginal cells and very characteristic hind legs in both sexes. Those of the female have an entirely white-haired hind tibia that contrasts with the very broadened, black-haired basitarsus. The male hind legs are less hairy but very swollen. Males have yellow faces.
M. europaea is a wetland specialist usually found in fen, open carr, reedbeds, ditches and water margins where its pollen source, Yellow Loosestrife, is present. It collects both the pollen and floral oils of this plant, and uses the oils to waterproof its nests, which are often constructed along paths and banks that become seasonally flooded. It will also visit a variety of other flowers growing in and around wetlands for nectar e.g. thistles, bramble and bird’s-foot trefoils. Adults fly from July until early September.
Records are almost entirely confined to south-east England from Dorset to Norfolk.