Here we have an Orange Yellow Sulfur butterfly nectaring on the wildflower Dakota Vervain. Colias urytheme is a highly variable butterfly in terms of its markings. However, the large orange spots on the upper wings and the black margins are sufficient to classify this specimen. This one lacks a large silver eyespot on the hindwing, but this is not enough to discount the identification.
This member of the Pieridae family (White & Sulphur butterflies) is found all over the United States and migrates into most of Canada. In this image, you can see the proboscis being rolled up as the butterfly prepares to move to another location.
In the last image, you can see the full wingspread as this butterfly lands on another Dakota Vervain flower head. Orange Yellow Sulfurs like open grassland habitats and feed on nectar from a large variety of wildflowers, and crops like alfalfa. This image shows a little blurriness on the left wing due to its motion. The breeze was blowing that day and caused this subject to move at inopportune times.