Art Shapiro's Butterfly Site - Cercyonis

Cercyonis oetus

admin — Sun, 28 May 2006 18:09:35 +0000

A species of the Great Basin, East slope and alpine zone of the Sierra Nevada. On our transect resident on Basin and Castle Peaks above tree-line on volcanic substrates, and in sagebrush-bitterbrush shrub-steppe along the east edge of Sierra Valley. Flies jerkily over the top of the vegetation, but lands frequently. Not a frequent flower visitor, but comes to Mule's Ears and Sulphur Flower, and late in the season to Rabbitbrush.

One brood; July-September in Sierra Valley; very late at Castle, generally the last species to emerge, in September and flying into October; a rare stray at Donner. Occurs on the volcanic mudflows at Anderson Peak and near Sugar Bowl (outside my site) and on Carpenter Ridge and Mount Lola as well. Hosts presumably perennial grasses.

Cercyonis pegala boopis

admin — Sun, 28 May 2006 18:09:34 +0000

Our representative of a transcontinental, polytypic species, the Ox-Eyed Satyr is local and usually uncommon in our region. On the transect it occurs at Gates Canyon, where it seemingly colonized only quite recently, and at Sierra Valley and is unrecorded elsewhere. It generally occurs along or near streams in grassland or foothill woodland. Although it occasionally visits flowers-especially Canada Thistle at Sierra Valley-, it is usually seen flying with an odd, jerky motion among tall grasses; if disturbed it often seeks shelter inside brambles or other thickets. Females are larger than males and often have a vaguely yellowish cloud surrounding the forewing eyespots above.

There is one brood, starting as early as May at Gates but in late June or July at Sierra Valley; in both places females may fly as late as October. The larval host plants are undetermined perennial grasses.

Cercyonis sthenele silvestris

admin — Sun, 28 May 2006 18:09:33 +0000

The currently-favored common name is misleading insofar as this species occurs widely in California west of the Great Basin. Like the other species of Cercyonis it is single-brooded, and the adults rather long-lived. On the transect it is abundant in grassland, shrub-steppe and alfalfa fields at Sierra Valley and occurs at lower density in brushy, rocky areas at Washington and Lang Crossing on the West slope. Adults fly low, near the ground, moving jerkily through the vegetation. They often sit on rocks or in paths but this is not territorial perching. They infrequently visit flowers, with Composites and Eriogonum nudum the most frequent choices. At all sites where it occurs, it flies primarily in June and July, with a few stragglers into autumn. There is a single record at Gates Canyon and one at Suisun, undoubtedly strays (from where?). On the West slope, there are subtle phenotypic differences between populations from the Yuba River drainage north and those from the American River south.