A female face fly is slightly darker than a female house fly, but is otherwise almost identical. The male face fly's abdomen is orange with a black band down the center. The puparium or pupal case of the face fly is unusual in that it is white. An easy field identification characteristic is that face flies congregate in clusters of 20 to 100 on the faces of cattle. Only the female face fly is a pest of livestock.
Males spend their time perched on vegetation, awaiting mates.
The males feed on plant nectar and on the liquid secretions of dung. Females feed on protein contained in eye secretions, nasal secretions, and saliva, not on blood. They feed only during the daytime, resting on fence posts or vegetation at night. While the fly is feeding, the roughness of its sponging mouthparts irritates the cow's eye and increases tear production. Face fly feeding can transmit bacteria to the eye, increasing the likelihood of bovine pinkeye and Thelazia eyeworms.