Lycaenidae

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.

Mitoura gryneus chalcosiva

The correct name for this entity is uncertain. Whatever you call it, it is abundant in Sierra Valley in late spring to early summer, and a few autumn individuals suggest at least the possibility of a second brood. The host is Juniper, Juniperus occidentalis. Males perch on the tree and form leks. They also puddle. Both sexes visit many flowers, especially Yarrow (Achillea) , Yellow Ivesia, Sulphur Flower (Eriogonum umbellatum), and Tansy Mustard (Descurainia). There is a great deal of minor variation in color and pattern.

Mitoura gryneus nelsoni

This is a member of a species complex in evolutionary ferment, apparently in the process of speciating on several host plants of the juniper-cypress family, Cupressaceae. Nelson's Hairstreak feeds on Incense Cedar, Calocedrus decurrens, and is generally abundant in mixed mesic forest at mid-elevation on the Sierran West slope; it occurs irregularly at Washington, near the lower end of its altitudinal range; swarms at Lang Crossing; and is a rare stray at Donner, above the range of Incense Cedar.

Mitoura johnsoni

An enigmatic species, usually rare but occasionally locally common for a generation. It breeds on pine mistletoes (genus Arceuthobium) on Gray or Foothill Pine (Pinus sabiniana) at low elevations and on Ponderosa and Jeffrey Pines (P. ponderosa, P. jeffreyi) higher.

Mitoura spinetorum

The steel-blue color on the upper surface is unique in our fauna. This handsome species is generally rare, occurring at our sites as singletons visiting mud puddles, or on Rabbitbrush in autumn. It can be locally common on serpentine, where Gray Pine (Pinus sabiniana) tends to be heavily infested with the butterfly's host, Pine Mistletoe (Arceuthobium). It appears to have 2 or 3 broods per year, but records on our transect are so spotty that the seasonal pattern is less than obvious. Males are territorial perchers high in trees.

Philotes sonorensis

This spectacularly beautiful butterfly occurs at Washington and Lang Crossing. It is intensely local on the West slope of the Sierra, flying along rocky cliffs in canyons where the host plant, the succulent Dudleya cymosa, grows; but it is not found in many places where the plant occurs. The butterfly emerges extremely early in the year and is thus easy to miss; often, when it is out, there is nothing in bloom for it to visit. It has been taken as early as late February at 5000' in a drought year. Usually it is out March-May at Washington and April-June at Lang.

Plebejus acmon

This species has been found at all sites on the transect, though it is not certain that it overwinters at Donner (some years) or Castle Peak (at all). It is weedy and highly dispersive. Although some of its host plants (Deer Weed, Lotus scoparius; Wild Buckwheats, especially the Eriogonum nudum group) are perennial and allow it to have >1 generation in the same place, many (annual species of Lotus, especially L. purshianus; Polygonum aviculare group) are ephemeral and do not. It thus has to be constantly on the move, looking for hosts.

Plebejus icarioides

Found at all of our sites except in the Sacramento Valley and Suisun. As recently as the 1970s it still had a presence in the Valley on Lupinus formosus, but seems to be gone now. An extremely variable species with several distinctive subspecies in the Bay Area. The Sierra Valley population frequently has the spot-pattern on the hindwing beneath "blind" or nearly so (white dots without or with only very reduced black centers, on an ashen ground). Similar specimens occur occasionally on Castle Peak. Males are avid puddlers and may be quite abundant.

Plebejus lupini

The name is a misnomer, since this butterfly always breeds on Wild Buckwheats (Eriogonum, family Polygonaceae) and has nothing to do with lupines. However, under the International Code of Zoological Nomenclature, there's nothing one can do about that! The butterfly is very similar to the Acmon Blue, but unlike it, is always single-brooded. Although there are a few lower-elevation colonies in the Sierra, on our transect it occurs only from Lang Crossing (5000') upslope, flying generally in late spring-early summer (May-July).

Plebejus saepiolus

Abundant on cool montane meadows, on our transect Lang Crossing and up (including Sierra Valley), where it flies just above the ground. The sexual dimorphism is extreme, and all our females are brown. High-altitude specimens may have the black spots beneath rather large and squarish. Adults visit low flowers, especially those of clovers, and males puddle. This species usually co-occurs with the Sonoran Skipper and the Nevada Cloudy-Wing and, often, with the Gray Blue.

Plebejus shasta

Despite its name, the Shasta Blue does not occur on Mount Shasta. It is a high-altitude species. It formerly occurred at Donner but seems to be extinct in my site, though it persists at 8000' at Sugar Bowl, e.g. It is common at Castle and Basin Peaks, occurring in alpine rock-garden habitats where it generally flies from mid-season onward (July-October), along with the Sooty Gossamer-Wing. It flies near ground level, often basking with wings open, and visits Sulphur Flower (Eriogonum umbellatum) more than any other flower.