Eristalinus

As the name suggests the two species in this genus are similar to small Eristalis species, but differ in have distinctively spotted eyes and no markings on the abdomen. At first glance they may appears to be dull black flies, but closer inspection will reveal a shiny abdomen and the uniquely patterned eyes.

Eristalinus sepulchralis - Striped thorax and dull patch on the abdomen - widespread in marshy areas

Eristalinus aeneus - Larger than sepulchralis and abdomen entirely glossy. Eyes hairy on the upper part only. Mainly coastal in UK.