Efficacy and dissipation of permethrin for the control of the northern fowl mite in hens.

Laying hens were treated with permethrin at the rate of 20 mg per bird to determine efficacy against northern fowl mites Ornithonyssus sylviarum (Canestrini and Fanzago) and the dissipation of residues over a 42-day period. Permethrin provided greater than 99% control of mites for at least 42 days posttreatment as compared to malathion which did not substantially reduce mite infestations. Carbaryl and coumaphos treatment resulted in limited reductions with mite populations recovering by two to three weeks posttreatment.