Ectoparasites of commercial poultry facilities have been significant economic pests for many decades. The two most common parasites found in caged laying operations are the chicken body louse (Menacanthus stramineus Nitzsch) and the northern fowl mite (Ornithonyssus sylviarum Canestrini & Fanzago). The presence of both these parasites on the same hen host has rarely been observed. Birds that ony had lice were challenged with the introduction of mites, and birds that only had mites were challenged with the introduction of lice. Within the span of less than 8 weeks, both groups of birds, with the exception of two, were infested only by the chicken body louse with no northern fowl mite observed. Hen beak condition (intact versus trimmed) is very important for ectoparasite population development, and may have an impact on the ability of mites to persist on a louse-infested host. Because the northern fowl mite is the most economically important poultry production pest, improved control measures, including cultural or biological, must be pursued to avoid economic losses and achieve sustainable control.