Art Shapiro's Butterfly Site - Pyrgus

Pyrgus communis

admin — Sun, 28 May 2006 18:07:45 +0000

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. These populations today breed largely on introduced weeds of the genus Malva (in the Sacramento Valley also on the native Alkali Mallow, Malvella leprosa, and on the now rare Checkerblooms, genus Sidalcea, in tule marshes). The other is single-brooded, occurs above 6000' (including Donner and Castle Peak) and breeds only on native Sidalcea. There are very slight "statistical" differences in pattern, but the genitalia are the same. There seem to be occasional strays of the lowland animal picked up at Donner, mainly late in the season. In southern California occurs a morphospecies, P. albescens, which differs from communis in genitalia and is, like it, multiple-brooded. This animal, however, is molecularly indistinguishable from the univoltine Sierran (genitalic) communis!

The lowland animal occurs anywhere in the open where hosts are nearby, including urban vacant lots and around ranch buildings and corrals. The montane animal occurs in open coniferous forest with Sidalcea in the understory, and along wood roads and paths. Both visit a great variety of flowers avidly. The flight seasons are March-November in the Central Valley, June-August in montane sites, and late March/April-October at Sierra Valley. (At Sierra Valley the univoltine animal is as close as the top of Yuba Pass.)

Males are perchers, generally well off the ground, and extremely energetic fliers. They often appear blue in flight (females, lacking the silky hairs, do not).

Pyrgus ruralis

admin — Sun, 28 May 2006 18:07:44 +0000

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.

Recorded sporadically as low as Washington; common at Donner and Castle Peak. An early flier, emerging 2 to 4 weeks after snowmelt, at Donner usually in June and gone before August; may be as early as May at its lower elevational limit. It usually flies with the Silvery Blue and Stella Orange-Tip at any given place. The species also occurs disjunctly in the high North Coast Range and coastside.

Pyrgus scriptura

admin — Sun, 28 May 2006 18:07:43 +0000

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.

Multiple-brooded, March through October, though in drought years it can enter diapause early and skip late-season breeding. Usually it is commonest in autumn, however. The only host plant in our area is Alkali Mallow, Malvella leprosa (formerly known as Sida hederacea!), a very long-lived perennial forming large colonies, with gray-felted, fluted foliage and creamy white flowers. This plant also occurs disjunctly in similar habitats in Mexico and in Argentina - in both places it has lemon-yellow flowers - and in eastern Argentine Patagonia another species of Checkered Skipper, not closely related to ours, specializes on it and is hardly distinguishable in color and pattern from P. scriptura. This is a striking case of convergent evolution.

Adults visit flowers with short corolla-tubes and growing near the ground, especially Lippia and Heliotrope.

This butterfly does not seem to be a very good colonizer; many colonies have been stable for decades, and many patches of host plant remain uncolonized although in close proximity to breeding populations. The lack of old collection records has nonetheless led some to speculate that the butterfly was introduced from southern California or the desert Southwest during the 20th Century.