Synonyms and other taxonomic changes
Melitaea sterope W. H. Edwards, 1870. Type locality: Oregon [restricted to “Tygh Valley, Wasco county, Oregon” by Bauer (1975), in: Howe, Butterflies of North America: 157 [This is the oldest and thus proper species name for this taxon; however, the name "acastus" is better known, more widely used, and there is a proposal to conserve the name acastus over sterope. The name sterope has traditionally but incorrectly been associated with the species Chlosyne palla.]
Chlosyne palla sterope (W. H. Edwards)
Chlosyne acastus sterope (W. H. Edwards) [invalid combination; a subspecies name cannot be older than species name it is included under]
Melitaea acastus W.H. Edwards, 1874. Type locality: “Montana; Nevada; southern Utah” [restricted to Provo Canyon, Utah County, Utah by F. Brown (1966), Transactions of the American Entomological Society 92(3): 402-403]
Chlosyne acastus (W.H. Edwards)
Chlosyne gabbii acastus (W.H. Edwards)
Melitaea neumoegeni Skinner, 1895. Type locality: Little Rock, Los Angeles County, California
Chlosyne acastus neumoegeni (Skinner)
Melitaea sabina W. G. Wright, 1905. Type locality: Sabino Canyon, Santa Catalina Mountains, Pima County, Arizona
Chlosyne acastus sabina (W. G. Wright)
Melitaea hewesi Leussler, 1931. Type locality: Tygh Valley, Wasco County, Oregon
Melitaea palla vallis-mortis J. Johnson, 1938. Type locality: Tuber Canyon SpringPanamint Mountains, Inyo County, California
Chlosyne acastus vallismortis (J. Johnson)
Chlosyne acastus dorothyi Bauer, 1975. Type locality: Durkee, Baker County, Oregon
Chlosyne acastus robusta Austin, 1998. Type locality: Kyle Canyon Campground, Spring Mountains, Clark County, Nevada
Chlosyne acastus waucoba J. Emmel, T. Emmel & Mattoon, 1998. Type locality: Cerro Gordo (town), Inyo Mountains, Inyo County, California
Chlosyne sterope (acastus) arkanyon M. Fisher & Scott, 2006. Type locality: Poncha Creek, south of Poncha Springs, Chaffee County, Colorado
Chlosyne acastus arkanyon (M. Fisher & Scott)
Range
This species is widespread, mostly in Sagebrush Country and southwestern deserts of the west.
Food
Assorted family Asteraceae - tribe Astereae, particularly (but not limited to) Chyrsothamnus, Machaeranthera, & Xylorhiza.
Remarks
Highly variable, with the percentage of dark and light markings above varying a lot, and sometimes with the orange in the middle replaced by something approaching white or yellow. (Comment by David J. Ferguson)