Musca autumnalis

De Geer, 1776

face fly, autumn housefly

, commonly known as the or autumn housefly, is a nonbiting muscid fly native to the Palearctic region that was introduced to North America in the 1940s–1950s. are obligate pests of cattle and horses, feeding on ocular and nasal secretions, tears, saliva, and blood from wounds. The exhibits pronounced seasonal , with peak abundance in late summer and autumn, and undergoes facultative in adults triggered by short and cool temperatures. Larval development occurs exclusively in fresh cattle , where larvae feed on microbial flora and fauna.

Musca autumnalis 109024394 by Cole Shoemaker. Used under a CC BY 4.0 license.

Musca autumnalis 71068033 by Ken-ichi Ueda. Used under a CC BY 4.0 license.

Musca autumnalis 22126972 by Michael Bakker Paiva. Used under a CC BY 4.0 license.

Pronunciation

How to pronounce Musca autumnalis: /ˈmʌska ˌɔːtəmˈneɪlɪs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

are slightly larger than the housefly (), averaging 7–8 mm in length. The body is grey with four dark longitudinal stripes on the and a grey-black patterned . Males have that nearly touch when viewed from above. Distinguished from M. domestica by larger size, distinct abdominal patterning, and ecological association with cattle rather than human structures.

Images

Habitat

Pastures and agricultural landscapes associated with cattle operations. Larval development occurs exclusively in fresh cattle ; rest on vegetation at night.

Distribution

Native to most of Europe, Central Asia, northern India, Pakistan, China, and parts of North Africa. Introduced to North America around the 1940s, now distributed from southern Canada through most temperate regions of the United States. Also introduced to St. Helena Island in the South Atlantic.

Seasonality

emerge from winter hibernation in March to early April. Multiple overlapping occur through late spring and summer, with 3–10 generations per year depending on weather. peaks in late summer and autumn. Adults enter facultative in autumn, triggered by short and cool temperatures, and overwinter in protected locations.

Diet

feed on manure juices, plant sugars, and secretions from cattle and horses around , mouth, and nostrils; also feed on blood from wounds such as horse-fly bites. Females require protein from animal for ovarian development. Larvae feed on microbial flora and fauna in fresh cattle .

Host Associations

cattle (Bos taurus) - primary obligate association; feed on secretions and larvae develop in
horses (Equus ferus caballus) - secondary feed on secretions but larvae do not develop in horse manure
Heterotylenchus autumnalis - that parasitizes , affecting mating and oviposition
Thelazia spp. - transmits eyeworm Thelazia rhodesi to cattle and horses

Life Cycle

Complete with four stages: , larva (three instars), pupa, and . Females deposit eggs on fresh cow manure within 15 minutes of deposition; eggs hatch within hours. Larvae pass through three instars, reaching approximately 12 mm, then develop into white pupae. Adults emerge 10–20 days after egg deposition depending on temperature. Multiple per year with overlapping generations after the first.

Behavior

Strong on cattle , particularly around and muzzle. Pronounced seasonal fluctuations with autumn peaks. avoid direct sunlight and high temperatures; rest on vegetation at night. of several kilometers documented. Females show higher fidelity to than males due to protein requirements for development.

Ecological Role

Larvae function as decomposers in . Competitor with other dung-inhabiting insects including other dipteran larvae. Potential for competitive exclusion of pest flies in dung. serve as intermediate and for parasitic including Thelazia eyeworms.

Human Relevance

Significant pest of cattle and horses causing irritation, reduced weight gains, and potential transmission. of Thelazia rhodesi (eyeworm) and suspected vector of infectious bovine keratoconjunctivitis (pinkeye). Documented case of Thelazia gulosa transmission to human in Oregon (2016) and California (2018). On-farm control by conventional means has proven ineffective due to and mobility; and sterile insect technique suggested as alternatives.

Similar Taxa

Musca domesticaSimilar size and general appearance; distinguished by smaller size (6–7 mm), less distinct abdominal patterning, association with human structures rather than cattle, and four thoracic stripes that are less sharply defined
Stomoxys calcitransBoth are cattle-associated muscid flies; distinguished by S. calcitrans being a blood-feeding biter with piercing mouthparts, while M. autumnalis is nonbiting and feeds only on secretions and wound blood

More Details

Parasite-mediated behavior modification

The Heterotylenchus autumnalis parasitizes face flies and has been observed to affect mating and oviposition in infected . The of the fly and nematode are synchronized, with both entering in autumn and together.

Larval distribution in dung

larvae exhibit specific horizontal and vertical distribution patterns within pats in response to temperature and moisture gradients, positioning themselves to optimize developmental conditions.