Parnassius smintheus, the Rocky Mountain parnassian or Rocky Mountain apollo, is a high-altitude butterfly found in the Rocky Mountains throughout the United States and Canada. It is a member of the snow Apollo genus (Parnassius) of the swallowtail family (Papilionidae). The butterfly ranges in color from white to pale yellow-brown, with red and black markings that indicate to predators it is unpalatable.

Parnassius smintheus primarily feeds on the leaves of the Sedum lanceolatum plant as larvae and on its nectar as adults. The butterfly tends to reside in meadows and avoids forests, because it strongly prefers light. The males of this species fly from meadow to meadow frequently to find females and food resources, whereas females are more likely to avoid flying. The males seem to have mate choice in this species, as they emerge from the pupae earlier than the females and patrol for females, heavily preferring newly emerged females that have not yet flown.

Although the species is not yet endangered, the climate change and human activity over the last few decades have reduced its viable habitats, and this process is continuing.

...