Hesperiidae

The skippers are a worldwide family of about 3500 species that appear to be "sister" to the rest of the "true butterflies". The clubs on the tips of the antennae are usually hooked. Our California skippers fall into two or three subfamilies: the spread-wing skippers (Pyrginae), the folded-wing skippers (Hesperiinae), and the Heteropterinae.

The spread-winged skippers are generally dark brown and hold both sets of their wings open when landed. They use a wide variety of hostplants, including oaks, Ceanothus, legumes, mallows, and even saltbush. California genera include PyrgusHeliopetesErynnisThorybesEpargyreus, and Pholisora.

The folded-wing skippers have a characteristic posture when they land: the forewings are held at a 45o angle to the rest of the body while the hindwing is held open and flat. This gives them a "fighter-jet" like appearance. They are largely orange and tawny, and many have whitish chevrons on the ventral hindwing, although some genera are dark brown. All members of this group feed on grasses or grassy-like plants (like sedges and rushes) as caterpillars, and as a result, they are often called the grass skippers. California genera include HesperiaOchlodesPolitesPoanesHylephilaLerodeaAmblyscirtes, and Atalopedes.

A third subfamily, the Heteropterinae, is weakly differentiated from the other skipper subfamilies, but the lone California representative is distinctive: Carterocephalus palaemon.

Amblyscirtes vialis

Local and generally uncommon; along roadsides and streamsides in dappled light and shade in moist habitats within forest; very local. Found in the Coast Range/Bay Area and on the Sierran West slope, foothills to (rarely) 7000'. It often co-occurs with the Arctic Skipper, Dreamy Duskywing, Western Tailed Blue, Clodius Parnassian, Gray-Veined White, etc. Males perch on leaves in sunflecks and occasionally visit mud puddles. There is no color or pattern variation, and the sexes are nearly identical.

Atalopedes campestris

Somewhat weedy, this robust skipper is often found breeding in mowed lawns and visiting garden flowers - famously, in Capitol Park in downtown Sacramento! Widespread near sea level and in the lower foothills; less common in the coastal fog belt than inland. In recent years this species has seemingly reacted to global warming by expanding its range from northern california to central Washington State and Idaho. More recently still, it has jumped the Sierra and invaded the western great Basin, becoming established in Sierra Valley, Carson Valley and near Verdi, NV.

Carterocephalus palaemon

The Arctic Skipper is not truly arctic, but is circumboreal, occurring in cool, wooded, usually streamside habitats across northern Eurasia and North America. Our transect is right at its southern range limit in California. There appears to be a small population near Washington, Nevada County which was discovered only a few years ago (though it was probably there all along; it occurs at low density and is not seen every year). There may be others on the West slope in similarly cool, wet, shaded places.

Epargyreus clarus

Locally common in the Western Sierra foothills and in the Coast Range north of the Bay. Formerly present (very locally) in the Sacramento Valley, but there are no current records. Found in riparian habitats, often in canyon bottoms, but something of a fixture in Gold Country towns where it breeds on introduced Black Locust (see below). There is nothing else in our fauna that can be confused with it.

Erynnis brizo lacustra

A narrow endemic in our fauna, restricted to serpentine soils in both the Coast Range and Sierra Nevada foothills, where its only known host plant in the North State, Leather Oak (Serpentine Scrub Oak), Quercus durata, occurs. Its southernmost population in our area is at Meadowbrook, near Georgetown. Farther south in both ranges it is not confined to serpentine and seems to use several shrubby oaks as hosts, but never in our area.

Erynnis funeralis

This species ranges from the San Joaquin Valley to central Argentina and Chile. In most places its host plant is cultivated Alfalfa (Medicago sativa)! It is only an accidental or stray species in our area. It can be told from the Mournful Dusky-Wing, E. tristis - which is common and resident - by its rather long, narrow, pointed forewing, often with a coppery-reddish cast. The shape of the forewing makes the hindwing look very broad. Multiple broods.

Erynnis icelus

Uncommon and rather poorly-known in California, this is a species of cool, moist forest - often seen along muddy streamsides, sitting with wings fully expanded. It ranges from the upper foothills to mid-elevation (roughly 1500 to 6000' at the latitude of I-80). The only other small Dusky-Wing with a "chain-dotted" forewing pattern is the larger, serpentine-endemic Sleepy Dusky-Wing, E. brizo lacustra. Note the squarish, "cut-off" forewing shape of E. icelus!

Erynnis pacuvius

An uncommon species found in both the Coast Range and Sierra Nevada, mostly in chaparral and along roads in mesic forest where it often puddles. Confusingly similar to the Persius Duskywing but always single-brooded, and usually identifiable by habitat and plant association. It has a gloss or lustre usually missing in the "matte" persius and lacks a white dot at the end of the forewing cell above. In fact, it is very dark. Late spring-early summer; host plants various species of Ceanothus; the reasons for its scarcity are unknown.

Erynnis persius

Locally common in a wide variety of habitats from sea level (including the Central Valley) to 7000',but rarely seen on the East slope. Many of its colonies are transient, especially at low elevation where its hosts are often annuals.It often disappears from an area for years on end, then reappears suddenly. It has, however, been a long-term permanent resident at Lang Crossing. This is the only small Dusky-Wing with multiple broods--three at 5000'. This in itself is a valuable aid to identification.

Erynnis propertius

Our commonest and most widespread Erynnis, easily recognized in our area by its large size, brown hindwing fringe, and two light spots near the outer angle of the hindwing beneath. It occurs from sea level to 9000', though the individuals seen above 7000' seem to be hilltopping fly-ups and there is no evidence of breeding up there (in fact, there are often no hosts). An avid puddler, often in large numbers, it occurs in woodlands and forests but is very nearly gone from the Central Valley.