Compared to chewing lice, symbiotic and studies on their biology, ecology and survival strategies are still rare. To describe the ecology and morphology of the mite species Proctophyllodes megaphyllus, a symbiont of the alpine accentor Prunella collaris, 150 accentors were captured in the West Carpathian Mountains of Slovakia. The mites extracted from the birds were sexed and their specific body structures were measured. In total 2144 individuals of P. megaphyllus were collected from 100 accentors. Male mites collected in autumn, after the bird's postnuptial moult, reached the largest size. At the same time, mite prevalence reached maximum while the mean intensity of infestation was at its lowest. Our results suggest that mites preferred newly coated feathers after a moult and radiated horizontally, infesting birds at shared roosting sites where alpine accentors tend to reoccur. This study is one of the few evaluations of seasonal variation in ecology and morphology of feather mites in alpine conditions.