Fairly common on the Sierran West slope in rocky canyons and moist forest. Local in the North Coast Range and on the East slope of the Sierra, usually in rocky canyon sites. Resembles (and easily confused with) the Gray-Veined White in flight; probably underreported. The female is larger than the male, with broader wings and a more complete dark patrtern at the apex; otherwise similar. The genus Anthocharis is Holarctic ; there are related species in the eastern United States, Mexico, Europe and East Asia.

(See also A.s.thoosa and A. stella.)

This is the East slope representative of the Sara Orange-Tip. In our area it is uncommon, found on lava flows and sagebrush-bitterbrush shrub-steppe north of Lake Tahoe. It is a little smaller than A. sara sara and has the black pattern a little heavier. Females may be slightly yellowish.

There is one brood in early spring (March-May at 5000'). The host plants are Rock Cresses (genus Arabis) and Tansy Mustard (Descurainia). Adults visit flowers of the hosts, as well as Fiddleneck, Wild Onion, and other early-spring flowers of the upland East slope.

Similar to the Sara Orange-Tip but the ground color is very pale yellow in the male and a warmer yellow in the female. There are many detail differences in the wing pattern, as well as a consistent difference in the venation of the forewing. Stella was formerly considered a subspecies of sara and is still so listed in some books. However, it co-occurs with both A. sara sara (Sierran West Slope) and A. sara thoosa (East Slope) in some places without interbreeding, as shown by molecular genetic studies, so we conclude that it has attained biological species status.

An uncommon grassland and shrub-steppe species on the Sierran east slope only, often seen near vernal pools. It is only accidental in Alfalfa fields and unlikely to stand out among swarms of the two Alfalfa-feeding Colias there; on theother hand, it is likely to be the only Colias flying through sagebrush and bitterbrush at, say, Beckwourth Pass. Pale females are extremely rare. The underside of the hindwing is uniform grayuish-green, and the silver discal spot has only one (purple) rim. On our transect only at Sierra Valley, and never common.

Ubiquitous except in closed-canopy forest; one of our commonest butterflies, often reaching very high densities in alfalfa fields in midsummer to autumn and becoming conspicuous at that time; when the alfalfa is cut may emigrate en masse, even flooding into cities. This is also our most variable butterfly, seasonally and individually. Cold-season specimens are small, very heavily infuscated on the ventral hindwing, with reduced black borders above, increased basal black above on all wings, and the orange pigment concentrated into discal patches on a bright-yellow ground.

The Yellow Sulphur of the West is different in many ways from the Eastern one and may be its own species (eriphyle). Both, however, hybridize readily with C. eurytheme where they co-occur, almost always in alfalfa fields. Our Yellow Sulphur occurs only East of the Sierran crest and is only a rare stray at Donner. But it is a permanent resident in Sierra Valley and other irrigated alfalfa-growing areas (e.g., Honey Lake to the north and Carson Valley to the south, and eastward across the Great Basin). It strays only infrequently to open wildlands.

Formerly common in the Central Valley, Delta, Bay Area and lower foothills, this species has suffered an unexplained crash and is teetering on the brink of regional extinction. It had been a great success story! From its biology we inferred that its native host plant was the tall mustard Guillenia (formerly Thelypodium) lasiophylla, now a rare plant in the Valley grasslands. It had successfully made the transition to naturalized annual species of Brassica and Raphanus and was doing very well through the 1980s.

See discussion of the three entities in this complex under E. hyantis hyantis

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Three different subspecies (two of them named) occur on our transect.