Site Utilization by Adults and Larvae of Mardon Skipper Butterfly (Polites mardon) at four sites in Washington and Oregon

The primary purpose of this case study was to ascertain whether the Polites mardon utilizes Festuca species as its oviposition plant. We surveyed two meadow sites on the Gifford Pinchot National Forest in Southern Washington, and two on the BLM lands of the Medford District in Southern Oregon, for oviposition plant associations of P. mardon. We conducted population censuses and observed general adult nectar behavior. Additionally we conducted larval searches, on 2 to 3 week intervals after the adult flight period. A major finding from this study is that P. mardon use more than one graminoid species for oviposition. The most common oviposition plants were Danthonia californica, Festuca idahoensis, and Carex species. In addition, P. mardon adults seem to use a variety of flower species for nectar. The most common observations were on Vicia species (Washington sites) and Potentilla diversifolia (Oregon sites). In the Southern Washington sites, populations included at least 125 and 343 individuals. In the Southern Oregon sites, populations included at least 41 and 128 individuals. We located 8 individual larvae, and plan to return in the spring to determine the over-winter life stage of this species.