Relationship of Feeding Activity of Face Fly (Musca autumnalis DeGeer) to Production of Keratoconjunctivitis in Calves

Abstract

SUMMARY In 2 experiments the feeding activity of laboratory-reared face flies, Musca autumnalis DeGeer (Diptera: Muscidae), was studied to determine the relative contribution of mechanical irritation and bacterial infection to the production of keratoconjunctivitis in calves kept in a screened enclosure. In the 1st experiment, calves were exposed for 9 days to flies which were uncontaminated with Moraxella bovis (Hauduroy); in the 2nd experiment, calves were exposed for 11 days to flies which were contaminated with M. bovis . The signs and lesions produced in both groups of calves were indicative of mild to moderate pinkeye: irritation and production of a serous or mucoid exudate. Appreciable differences in gross and microscopic lesions were not observed between experiments, and the eye itself was not involved. Results of cultural examinations of the eye secretions of calves in the 1st experiment were negative for M. bovis , and those of the eye secretions of calves in the 2nd experiment were positive for M. bovis . The face fly apparently is a significant contributor to bovine keratoconjunctivitis.