Technical Bulletin 81B
The face fly is similar in appearance to the house fly (Figure 1) with a few minor differences. The female face fly is somewhat larger and darker. The large eyes of the male face fly nearly touch on the front of the head while the eyes of the house fly are further apart. The female face fly has a silvery stripe around the eyes whereas the stripe on the house fly is more golden. A dark spot between the eyes of the face fly is more rounded than that of the house fly and the abdomen of the face fly is darker and more slate-grey in color.
South Dakota State University
Easton, Emmett R.; Au Yeung, Sui Shan; and Lysyk, Timothy J., "Progress Toward Establishing a Pest Management Program for the Face Fly, Musca autumnalis DeGeer, in South Dakota" (1985). Agricultural Experiment Station Technical Bulletins (1939-2011). 8.