There are twenty-eight species of gossamer-wing butterflies in Yellowstone, including the 11 in the subfamily Polyommatinae called “blues”. Blues, scarcely an inch across, are butterflies that eat nectar, mud, and dung. Each species has different host plants such as sulfur buckwheat, wild rose, and lupine. This small group of blues perched on a water saturated log next to a spring. They sipped mineral rich water from the log in an idyllic, cool and shaded refuge.