Control of northern fowl mite with permethrin and fenvalerate, two synthetic pyrethroid compounds

Trials were conducted to evaluate the efficacy of permethrin and fenvalerate, two synthetic pyrethroid compounds, for the control of the northern fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago), on White Leghorn hens. Fenvalerate at .0125%, .025%, and .05% active ingredient (ai) were as effective as carbaryl at .5% ai for 56 days posttreatment. Permethrin at .01%, .025%, and .05% ai were as effective, or better than, malathion at .27% ai for 56 days posttreatment. All treatments were applied to the birds as high pressure sprays.