Euphydryas chalcedona

admin — Sun, 28 May 2006 18:09:09 +0000

Common in both the Coast Range and Sierra foothills, to 5000'; absent at Donner and Castle Peak; common in Sierra Valley; absent from the Sacramento Valley and Suisun. Populations in the Coast Range have mostly black larvae with orange markings and little if any white. Populations from the lower foothills (beginning at Sailor Bar, Fair Oaks, Sacramento Co.) eastward have strong lengthwise white larval striping. There are numerous "statistical" differences between Sierran East and West slope adults, and the East slope populations, including Sierra Valley, include some strongly reddish individuals transitional to the high-altitude subspecies sierra. Populations at both Lang and Sierra Valley (5000', W and E slopes respectively) often emerge simultaneously or even a little earlier than those at Gates Canyon, at much lower altitude (!). A butterfly of chaparral and canyon riparian habitats and of gullies ansd streambeds in grassland or shrub-steppe on the E slope. Our populations (unlike some others) are not highly variable.

One brood, April-July. Males are territorial perchers. Adults visit many flowers, including California Buckeye, Squawbush (Skunkbush, Lemonade Berry), Yerba Santa, thistles, etc. Eggs are laid in masses; the young larvae feed in a web prior to diapause but singly thereafter. Hosts Scrophulariaceae (in the traditional sense) containing iridoid glycosides (bitter compounds probably mobilized for defense): Bush Monkeyflower (Mimulus aurantiacus), Bee Plant (Scrophularia), various species of Penstemon and Keckiella; can be reared on Plantago but not known to use it in the wild. There are numerous potential hosts at Donner and it is not at all obvious why there is no resident population in the entire area.

Euphydryas editha

admin — Sun, 28 May 2006 18:09:08 +0000

This colonial species is divided into numerous taxonomic subspecies. Since none of our populations belongs to a legally-protected subspecies, we will ignore the trinomials here. Much more local than E. chalcedona, usually flying earlier, and in our area easily told from it by the rounded wings, reduced black above, lack of white spots on abdomen, and partly-black antennal club. Many populations occur on serpentine. On our transect the only population west of the Sierran crest is at Washington. There are numerous populations nearby, as at Iowa Hill Road (Colfax) or Dutch Flat Powerhouse Road. There is an unusual population on top of Grouse Ridge, colored like the very small alpine subspecies nubigena but almost as large as foothill animals. This may be the source of the strays occasionally found hilltopping on Castle or Basin Peak--or there may be other mountaintop populations undiscovered nearby. There is a population at Sierra Valley on the lava flow. Males puddle; both sexes visit a variety of mostly low flowers but will rise to Yerba Santa, milkweeds, and even (rarely) Coffeeberry! It is insanely devoted to the flowers of the odd yellow Composite Chaenactis glabriuscula, often visiting no other yellow Comps. One brood, March-June, the flight season varying from year to year at a given site in response to weather. The part-grown larvae diapause and can carry over to a second year in the event of drought. The host in the western Sierran foothills is generally Collinsia (Chinese Houses) and at Sierraville, a small Orthocarpus (Owl's Clover) (both Scrophulariaceae). A variety of Scrophs and Plantaginaceae may be used in different sites, even close by.

Art Shapiro's Butterfly Site - Euphydryas

Euphydryas chalcedona

Euphydryas editha