The Mormon metalmark (Apodemia mormo) is widely distributed throughout western North America. The species exists in two peripheral populations in Canada and is listed as threatened in Saskatchewan and endangered in British Columbia. In Saskatchewan, this butterfly relies on Eriogonum pauciflorum for larval food and as its primary nectar source; however, presence of its host plant is insufficient to define habitats actually utilized by the butterfly. We investigated microhabitat characteristics that might explain habitat use of A. mormo adults using 102 host plant quadrats in which the butterfly was occupied (present) or unoccupied (absent) in Grasslands National Park and the Val Marie Community Pasture, Saskatchewan. Linear discriminant analysis demonstrated significant differences between occupied and unoccupied quadrats. Apodemia mormo was found disproportionately in quadrats with a combination of the following variables: higher percent bare ground and soil pH, steeper slope, southerly to southwesterly aspect, lower elevation, and lower soil nitrogen. Our results show that habitat use by A. mormo butterflies is correlated with environmental factors that define, either directly or indirectly, the local probability of association with host populations.