The effects of the northern fowl mite, Ornithonyssus sylivarium on egg production and body weight of caged White Leghorn hens.

Egg production of caged White Leghorn hens with heavy (greater than 1000) populations of the northen fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago), was 5 to 15% less than egg production of control hens. Body weight was depressed in hens infested with mites before the hens came into full egg production but not when hens were infested after that time. Feed consumption was not affected by mite populations.