Face fly

Definition

A non-biting muscid fly (Musca autumnalis) that aggregates on the faces of cattle and horses to feed on ocular and nasal secretions, mucus, and blood at wound sites. Adults are strong fliers that spend little time on the host, resting instead on vegetation or structures; larvae develop in fresh cattle dung. The species is a significant nuisance pest in temperate livestock systems and a mechanical vector of the eyeworm Thelazia and the causative agent of pinkeye (Moraxella bovis).

Etymology

Common name refers to the fly's habit of clustering around the eyes and muzzle of large mammals.

Example

Face flies are most abundant on cattle in open pasture during summer mornings; control relies on ear tags containing pyrethroids rather than whole-animal sprays because the insects visit the host only briefly.

Synonyms

• autumn housefly

Related Terms

• Musca autumnalis
• horn fly
• Stable fly
• mechanical vector
• Thelazia
• Integrated Pest Management
• Ear tag

Usage Notes

Distinguished from the closely related housefly (Musca domestica) by behavior (face association vs. synanthropy) and from the horn fly (Haematobia irritans) by feeding strategy (non-biting secretophagous vs. obligate blood-feeding). 'Face fly' is sometimes used loosely for any muscid on livestock faces, but properly refers only to M. autumnalis in North American veterinary contexts. The species is native to Eurasia and invasive in the Americas.