As I drove past the Rabbitbrush (Chrysothamnus nauseosus), a common native plant of the western United States, I saw it was covered with these medium sized orange-brown butterflies.
First we had to remember how to tell a butterfly from a moth. The overlapping wings and bulb ended antennae are indicative of butterflies, along with the way the insects rest with the wings open or erect. A quick check in Butterflies and Moths: A Golden Guide Book, leads me to call this one Silver Bordered Fritillary (Boloria selene).
Wyoming Life 