University of Arkansas, Fayetteville Division of Agriculture


The northern fowl mite (NFM), Ornithonyssus sylviarum, is a commonly occurring external parasite of chickens. Primarily, caged layers have the greatest incidence of this mite, with bird unrest, unthriftiness and lowered production as some of the adverse effects of the infestation. In the current study, birds with natural NFM infestations were randomized into five treatment groups, placed in individual cages in treatment-specific batteries (all in one room), and evaluated for 28 d for infestation quantification by way of index scoring and feather digest. No treatments were 100% effective in eliminating all life stages of the mite. Tetrachlorvinphos in combination with dichlorvos (RAVAP E.C.® Boehringer Ingelheim) was the most effective with consistently negative post-treatment index scores and the greatest decrease in mite life stages (eggs, larvae, and nymphs/adults). Malathion dust (Hi-Yield® Voluntary Purchasing Groups, Inc.) and 10% garlic oil were next in level of effectiveness, with significant (P < 0.05) post-treatment reductions in both index scores and mite life-stage populations. Permethrin (Permectrin II® Boehringer Ingelheim) provided the least control of the infestations, with no significant reductions in index scores and only slight reduction in the abundance of life stages after treatment.