The Gossamer-wings are a very diverse and complex family with at least 4750 species worldwide. In California, they can be grouped into the coppers (subfamily Lycaeninae), the blues (subfamily Polyommatinae), and the hairstreaks (subfamily Theclinae). Many species have mutualistic relationships with ants (myrmecophily) where the caterpillar excretes complex carbohydrates through specialized glands for the ants (similar to aphids). In return, the ants defend the caterpillar from predators and parasitoids. While this relationship is usually facultative, the mutualism turns into trickery in some Lycaenid species and the butterfly caterpillars switch from being herbivores to become obligate predators on ant larvae inside the ant mound. As long as the caterpillar continues to produces sugary rewards for the ants, the ants are willing to accept, or are oblivious to, the carnage around them. Other Lycaenid caterpillars are predators on aphids being tended by ants.

Agriades podarce

This is a member of a circumboreal complex seemingly undergoing speciation even as we speak. Our populations are highly localized with the host plant along streamsides in wet and boggy high-altitude meadows. At Donner they occur in a small part of the Lake VanNorden Meadows and also on a couple of small boggy meadows upslope from Clair Tappaan Lodge and Cal Lodge. At Castle Peak they occupy a small portion of Castle Valley.

Atlides halesus

The common name is a misnomer insofar as there is no purple anywhere on this very showy, tropical-looking animal. The Great Purple Hairstreak occurs from sea level to about 5000' wherever its host plants, broadleaf mistletoes, occur. It is commonest in Valley and foothill riparian forest and in older urban neighborhoods with a well-developed canopy, and in foothill woodland. In recent years this species, which had turned up as a presumed stray in autumn on Rabbitbrush, became established as a breeding resident at Sierra Valley.

Brephidium exile

This species demonstrates classic source-sink metapopulation dynamics. West of the Sierra it overwinters successfully only very locally, usually on alkali soils with the favored native host plant Suaeda (Chenopodiaceae) but not subject to flooding. At these sites it breeds all winter, except in the coldest weather.

Callophrys dumetorum

The taxonomy and the limits of species in this complex are up for grabs, with wildly discordant interpretations to be found in the current literature. For purposes of this project the name dumetorum is being used in the usual sense of recent decades, for the low-elevation, inland entity in California. It occurs in chaparral, coastal scrub, rocky foothill canyons and lower-montane chaparral and rock gardens. It is slightly larger than the higher-altitude entity (with which it is sympatric at Lang!) and less bluish-green below. Males are territorial perchers. Occasionally common.

Callophrys sheridanii lemberti

The correct taxonomy of all our little green hairstreaks is up for grabs. At any rate, this is a high montane-to-alpine animal, found from Lang (where it co-occurs with C. dumetorum) through Donner to Castle Peak and (formerly) Sierra Valley. It flies in very early spring (which can mean July at high elevation!), shortly after snowmelt, typically in subalpine or alpine "rock gardens" in association with various wild buckwheats (Eriogonum) which are its presumed hosts.

Celastrina ladon echo

Common to abundant at all but the Sacramento Valley sites and Castle Peak, where near its altitudinal limit. Formerly occurred at North Sacramento, but now extinct (?). A devout mud puddler (males only); both sexes visit many flowers, especially Ceanothus and California Buckeye, both of which are hosts of the larvae. There is little variation in our area; second brood specimens are larger and brighter. Two broods in the foothills (January-April, May-July) and one at and above 5000' (May-July).

Euphilotes battoides

This is a "complex" of several biological entities which may be "good species;" we have much to learn. All the populations along our transect are in the Sierra Nevada and are associated with Sulphur Flower, Eriogonum umbellatum - which itself may be more than one species! The butterflies are always single-brooded and emerge when their hosts (which are their principal, if not sole nectar sources) are in bloom, generally in late spring-early summer. Males are avid puddlers.

Euphilotes enoptes

Like the Square-Spotted Blue, this is a "complex" of entities in evolutionary ferment. However, along our transect there is no such complexity. All of our populations, from the Sierra foothills over the crest, feed on the Eriogonum nudum group of Wild Buckwheats and have very similar life histories - one brood in late spring-early summer, matching the blooming time of the host. Adults rarely stray more than a few feet from the host, although males do puddle. They mate on the host and roost on it for the night.

Everes amyntula

Slightly larger and broader-winged than the Eastern Tailed Blue, with a grayer underside with smaller black dots and (often) stronger metallic scales near the base of the tail. This is a species of cool, moist habitats, from the Redwoods to the Sierran mid-West slope; it is completely absent from the Central Valley and typical E. comyntas habitats, and the two very rarely co-occur. (They may, however, hybridize where they do.) In the Sierra it occurs from 2500' upslope, and has a distinctive "ecotype" or ecological race above tree-line (e.g., on Castle Peak).

Everes comyntas

Like many Central Valley butterflies, this has been accused of being an introduction from somewhere else--but there is no good reason for thinking that it is. (We have done the molecular genetics which, alas, is uninformative.) The fact that it occurs widely and happily in disturbed habitats (in this case, annual grassland, riparian habitats and tule marsh) and often uses naturalized host plants contributes to the notion. It rarely turns up above 2000' and in our area is almost never sympatric with the Western Tailed Blue.