Numbers
localized to certain habitats; populations often fluctuate in numbers from year to year
one of 5 species in this genus in North America listed at
nearctica.comSize
wingspan 30-48 mm in Canada (
Butterflies of Canada); 38-51 mm in United States (
nearctica.com)
Identification
Adult: forewing upperside chalky white with large black discal spot (black bar that touches costa) with extensive dusting of white scales, and dark pattern at apex; underside of hindwing with dense reticulate pattern of yellowish-green marbling
Larva: body dark bluish-gray with many black dots and lengthwise bands of yellow and white
Range
mostly western North America (Alaska and Yukon to northwestern Ontario south of the treeline, south through Minnesota to northern New Mexico, west to California)
Habitat
generally open forested areas, particularly around pines; may be found in valleys, hillsides, meadows, and other open sunny areas
Season
adults fly from April to July in the north; in central California, flies from February to April and again from May to August; flight is a relatively slow zigzagging pattern
Food
larvae feed on a wide variety of members of the mustard family, including
Tower Rockcress (
Arabis glabra),
Drummond's Rockcress (
Arabis drummondii),
Dyer's Woad (
Isatis tinctoria), and
Tumble Mustard (
Sisymbrium altissimum)
adults nectar on flowers of the mustard family and other plants such as fiddleneck (Amsinckia spp.) and brodiaeas
Life Cycle
female lays single egg on flower bud of host plant; overwinters as a pupa inside chrysalis; one generation per year
See Also
Olympia Marble (
E. olympia) hindwing underside has three distinct bands with large white spaces between; Northern Marble (
E. creusa) forewing upperside has small discal spot, and hindwing underside has dark olive marbling, not yellowish-green (
compare images of several species)
also see
CBIF for a detailed description of differences among similar species
Internet References
pinned adult images plus description, biology, flight season, foodplants, habitat, distribution, US range map (nearctica.com)
pinned adult image plus description, distribution, similar species, foodplants, status, flight season, habitat, remarks (Butterflies of Canada)
