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Certain moose (Alces alces) populations in the northeastern United States are in decline because of increasing frequency of winter tick (Dermacentor albipictus) epizootics characterized by high calf mortality and reduced productivity in the population. Previous research identified soil fungi in wallows of bull moose that are pathogenic to larval winter ticks. We analysed skin/hair samples of moose harvested in Maine, USA, to further understand this fungus–tick–moose relationship. A total of 32 keratinophilic fungi from moose fur and skins were isolated, predominately Penicillium, Cladosporium, Aspergillus, Alternaria, Trichoderma, Beauveria, and Scopulariopsis. Each displayed pathogenic activity against unfed winter tick larvae (sole infestation stage) by topical application of spore inoculums and Koch's postulates. Bulls had more entomopathogenic fungi, pathogenic fungal isolates to ticks, and infected larvae than cows and calves. We propose a disease cycle with interactions of soil fungi, moose, and on-host winter tick larvae killed by entomopathogenic soil fungi. Bull moose presumably experience enhanced exposure and protection from abundant soil fungi due to their wallowing behaviour during the breeding season that is coincidental with questing by winter tick larvae. [ABSTRACT FROM AUTHOR]