A few weeks ago Leonard and I were at the Dan Ryan Meadow along Ash Creek (Lassen County CA) with friends. While everyone else fished I enjoyed myself photographing butterflies feeding on rabbitbtush (Chrysothamnus nauseosus). It was warm and late in the day. The butterflies were not in any hurry and, for once, proved to be good subjects.
Among the butterflies I photographed that afternoon were juba skippers (Hesperia juba). Skippers belong to the same order (Lepidoptera) as butterflies and moths, however are classified in a different superfamily than butterflies. Skippers are distinguished from “true” butterflies by their antennae, which are further apart at the base and have an enlarged tip that is expanded and tapers to a thin hook. Generally, skippers also have bodies that are more robust and moth-like than butterflies. Also, skippers at rest hold their wings at an oblique angle or laterally while butterflies tend to hold their wings pressed together above their bodies.
Juba skippers have orange brown wings with a dark border that tooths inward. The underside of their wings are light brown with jagged white spots. Like most butterflies skippers have a hollow, coiled proboscis that can be as long as their body. The proboscis unrolls into a sucking tube through which the adult feeds on nectar or other liquids. The coiled and uncoiled probosces can be seen in the pictures. Juba skipper caterpillars have a neck-like constriction behind the head.
The adult female lays a single egg near host plants. The caterpillar (larva) feeds on the leaves of grasses (hairgrasses, bluegrasses, needle grasses and bromes among other grass species). During the day the caterpillar rests between leaves that are loosely pulled together with silken strands. The pupa is formed inside pulled-together leaves, usually near the ground. Adults feed on nectar from flowers, especially rabbitbrush. There are two broods (generations) per season. It is thought that juba skipper larva (caterpillars) hibernate over the winter.
Juba skippers are found in sagebrush regions from the Pacific Coast east to Colorado.