The Face Fly

Common Name:
Face Flies
Scientific Name:
Musca Autumnalis DeGeer


The common name of face fly comes from the adult habit of feeding on the mucus and watery secretions found around the eyes, nostrils, and mouths of cattle. They are a nuisance pest in structures where their behavior resembles that of cluster flies, coming in to overwinter and being active on warm winter days. In the early 1950's, face flies were introduced from the Old World and are now found throughout most of the United States and Canada.


Adults about 1/4" (6.5-7 mm) long, about house fly size or slightly larger. Color dull gray; head with parafrontals (sides of front next to eye) bright gray, wide, nearly as wide as median frontal strips; thorax with 4 narrow black longitudinal stripes on dorsum; no pale spot behind head or on soutellum (rear tip of thorax); abdomen with dorsum entirely black in ground color, with gray and black pattern. Mouthparts sponging. Female with eyes much more widely separated than on male, male's almost touching. Wing with 4th (3rd long) vain (M) sharply bent forward near tip, towards and almost meeting 3rd vein at wing margin; with strong tuft of bristles at base of calypter (flat basal lobe; best seen by lifting upper calypter/lobe).

Mature larva about 1/4-7/16" (7-11 mm) long; eyeless, legless, and tapering towards head from large rounded rear segment, head represented by 1 pair of dark hooks. Color yellowish. Posterior spiracies (breathing pores) with spiracular area smooth and dark, 2 plates each with spiracular openings sinuous/winding slits which may/may not be surrounded by a thin black ridge (peritreme), button (round eedysial/molting scar) away from margin towards center, not attached to peritreme/margin.


  1. House fly (Musca domestics) with wing calypter (basal lobe) lacking bristle tuft, male with eyes well separated, female head with parafrontals (sides of front) each about 1/3 width of median frontal stripe.

  2. Flesh flies (Sarcophagidae) have only 3 dark longitudinal stripes on thorax, tip of abdomen usually red/pink.

  3. Stable (Stomoxys calcitrans) and False Stable (Muscina stabutans) flies have wing with 4th (3rd long) vein (M) curved towards 3rd vein but not sharply angled; in addition stable flies have piercing mouthparts and thorax with pals spot behind head while false stable flies have sponging mouthparts but a pale scutellum (rear tip of thorax).

  4. Little house (Fannia canicularis) and latrine (F scalaris) flies have wing with 4th (3rd long) vein (M) straight.

  5. Cluster fly (Pollania rudis) with golden hairs on thorax, thorax lacks 4 dark longitudinal stripes.


Females lay their eggs (30-230) only in fresh (less than 1 day old), undisturbed cow droppings/manure. The eggs are deposited just below the surface and have a black respiratory stalk on one end. Eggs hatch in 10-23 hours. The 3 larval instars require about 3-4 days. Last instar larvae migrate from inches to 30 ft (9.1 m) from the dropping to pupate in the soil. The pupal stage lasts about IO days. Developmental time (egg to adult) outdoors requires about 17-18 days at 77-86'F/25-30'0. Non- overwintering adults live up to 55 days.


Face flies are present outside from April to October, with numbers building up towards autumn. When the temperature is about 60'F/16'C, large numbers of primarily female flies cluster around the faces of cattle and horses where they feed on the mucus and watery secretions around the eyes, nostrils, and mouth. They also feed on the blood coming from wounds made by biting flies and on dung fluids. Males feed primarily on flower nectar. During the day, adults can also be found frequenting bushes, tall pasture grasses and weeds, fence posts, and rocks, in addition to the animals. In dispersal studies, marked flies were recovered up to 0.9 miles (1,500 m) away 46 hours after release; they are known to travel up to 20 miles (32 km).

Females lay their eggs only in fresh dung, preferably less than 1 hour old. The dung must be undisturbed which means breeding sites are in pastures and on range land.

Adults seek sheltered locations in which to overwinter beginning in late August or September. Such places include attics, wall voids, and basements of structures especially on the south and west sides of the structure. They tend to use the same structure year after year.

They can be a problem or nuisance in the autumn, winter, and/or spring; autumn when they enter to hibernate; on warm, sunny winter days; and again in the spring when they attempt to leave the structure. They can be stimulated by warmth to resume activity almost any time. Sometimes it takes no more than the furnace to be turned on and thoroughly warm the inside of the structure to start activity, but it usually additionally requires a bright sunny day to warm the walls from the outside. Once stimulated, face flies seek light. This is why they usually come out around loose-fitting wall switches and outlets, ceiling fixtures, window and door frames, window pulleys, etc. Face flies can usually be found at windows crawling on the panes or frames, or around lamps or lights.