Rocky Mountain Parnassian Butterfly (Parnassius smintheus): After spending the winter as an egg, this beautiful caterpillar has already grown a lot and is in its final stage (L5) before transforming into the pupal stage for its final, magical transformation into an adult butterfly. The caterpillars feed on species of stonecrop plants (Sedum). Photo by Glenn Marangelo on 5/12/17 near Drummond, MT.