Great Basin Naturalist


Pollen grains of plants with well-defined flowering seasons may persist on insects through episodes of dormancy, such as hibernation. When readily recognizable and possibly confounding taxa can be excluded, these pollen grains can serve as direct evidence of life-history phenomena that are notoriously difficult to verify in the field. Pollen of the autumn-flowering composite Chrysothamnus nauseosus was used to demonstrate that the common montane skipper, Hesperia juba, hibernates as an adult in Sierra Nevada. This is the first demonstration of adult overwintering in a temperate-zone hesperiid and may represent the smallest butterfly known to overwinter in a cold climate.