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.

Pyrgus communis

This familiar insect appears to be found from sea level to tree line-but things are more complicated than that. At the molecular-genetic level, the populations along our transect are apparently two different species. One is multiple-brooded and occurs as high as Lang Crossing (5000') on the Sierran West slope, and then again in Sierra Valley at 5000' on the East slope.

Pyrgus ruralis

A species of cool, moist montane meadows and their edges, where the host plants (Horkelia, family Rosaceae) grow. However, adults can often be seen flying along paths or trails and perching on bare ground there. They are low fliers and addicted to Pussy-Paws, but will visit other early flowers with short corollas as available. They do not visit flowers of their host plant.

Pyrgus scriptura

Local but sometimes common with its host plant in the Central Valley and Delta, generally on compacted alkaline clay soils. The Small Checkered Skipper has a "busy" flight just above the ground like a bee. The first brood is phenotypically very similar to the Two-Banded Skipper (with which it never co-occurs), but summer broods are smaller and very dark above, with the white markings reduced to tiny spots. Males fly along roadsides and if perching, sit at ground level.

Thorybes diversus

One of the scarcest and least-known butterflies in California, found erratically in glades in mesic forest on the Sierran mid-West slope and (more commonly) in the Trinity Alps of northwestern California. We know extremely little of its biology. One brood, May-July. Host plants presumably Fabaceae. Because this is so similar to the relatively common, widespread Northern Cloudy-Wing, T. pylades, and overlaps it at the upper end of pylades' altitudinal taxon range, it may be overlooked regularly. Watch for it!

Thorybes mexicana nevada

Found on and at the margins of wet meadows at and above Lang, extending above tree-line. Males may hilltop, and also puddle. Numbers of this species vary greatly among years; occasionally very common, usually not. It sits with the wings mostly or fully opened. Visits clovers, vetches, and Pink Pussy Paws eagerly. One brood, May-July; hosts clovers (Trifolium).

Thorybes pylades

A generally uncommon skipper of canyon-riparian and mesic habitats, from the foothills to 5000'. It sits with the wings only partly open, unlike most of its relatives. A strong flier but regularly seen at flowers, including Dogbane, Yerba Santa, Brodieas, California Buckeye, and Vetches; not much of a puddler. One brood in late spring (mid March-July, depending on altitude). Host plants: Fabaceae, especially the robust perennial Lotus crassifolius; native Lathyrus; Psoralea; possibly on Astragalus, but not recorded in our area.