•The northern fowl mite, Ornithonyssus sylviarum, is an economically important ectoparasite of poultry.•Control of northern fowl mite currently depends on spraying chemical insecticides.•Mites are resistant to many chemical classes, and control will be impacted by organic production and cage-free housing.•Knowledge gaps remain for this mite, and the development of future control methods will rely on basic and applied research on this ectoparasite. The northern fowl mite, Ornithonyssus sylviarum (Canestrini & Fanzago, 1877), is found on several continents and has been a major pest of poultry in the United States for nearly a century. Lack of earlier USA reports in the United States suggests an introduction or change to pest status in domestic poultry systems occurred in the early 1900s. Though predominantly a nest-parasite of wild birds, this obligate hematophagous mite is a permanent ectoparasite on domestic birds, especially egg-laying chickens. Economic damage is incurred by direct blood feeding and activation of the of host’s immune responses. This in turn causes decreased egg production and feed conversion efficiency, and severe infestations can cause anemia or death to birds. Here we review the biology, ecology, and recent control measures for the northern fowl mite. Photomicrographs are included of adult males and females, protonymphs, and larvae with key characters indicated. Special emphasis is placed on current knowledge gaps of basic and applied science importance.