Death Valley Natural History Association September E-Newsletter

Any time you are at Ash Meadows, from early Spring through the Fall, if you see a tiny butterfly flying around visiting wildflowers, chances are it is a western pygmy blue butterfly (Brephidium exilis). These butterflies are probably the most common butterfly on the refuge. Their size is about two-thirds of an inch tall and wide with their wings in the upright resting position, making them the smallest butterfly in North America. With their rapid flight patterns, one may only notice a small, fast-moving insect, on which it is hard to see any details. They are actually found in many parts of the United States and Mexico, but have also spread to the middle east. So, what makes them so influential at Ash Meadows? The principal groups of plants which the western pygmy blue lays its eggs on are various species of saltbush (Atriplex), of which seven species common on the Refuge. When the eggs hatch, the caterpillars have no problem with a lack of these plants to feed on. When the caterpillars metamorphize into adult butterflies, their diet changes to nectar, and they are well adapted to feeding on a variety of flowers. They have been seen on different flower species, and while feeding on nectar, they come into contact with the various flower parts, including the pollen-bearing stamens and the pistils, to which the pollen is transferred. Therefore, these butterflies are responsible for the fertilization and seeding production of various flower species. Among the species benefitting from visits by these butterflies are the Ash Meadows sunray, a species listed as Threatened under the Endangered Species Act and the alkali mariposa lily, considered one of the species of concern and endemic to southern Nevada and California. However, these are just two of the species visited, other species are also benefited, such as the species of globe mallows, orange flowers found throughout the Mojave Desert in the spring; salt heliotropes, and on desert milkweeds just to name a few plant species visited.