Chryxus Arctic
Oeneis chryxus
Description 1 3/4-2" (44-51 mm). Above, tan or tawny-brown to dark brown; male has dark sex patch across cell and surrounding dark region sometimes covering much of FW, leaving tawny marginal band. Below, FW tawny; male's FW crossed by dark line shaped like a bird's beak (female has line but much vaguer), mottled and striated brown and white; HW crossed by broad and prominent brown median band. Usually 2 or 3 eyespots above and below on FW, 1 on HW outer angle (tornus); eyespots may be obscure or well-developed.
Similar Species Great Arctic and Canada Arctic larger, have dark margins, bigger eyespots, and plainer undersides. Alberta Arctic smaller, duller. Uhler's Arctic smaller, lacks bird's beak marking and male's sex patch. California Arctic much paler gray-brown or whitish.
Life Cycle Egg white. Mature caterpillar, to 1 1/4" (32 mm), striped lengthwise with straw-color, olive, green, brown, and brownish-yellow; overwinters when young, some taking 2 years to mature.
Host plants are grasses (Poaceae), possibly Idaho fescue (Festuca idahoensis) in Washington. Chrysalis pale yellowish-brown with
dark brown head and wing cases.
Flight 1 brood; May-August, exact period depending upon local conditions.
Habitat Arctic and alpine tundra, evergreen forest clearings, mountain meadows and sage flats, northern prairies and parklands, and shaly steep slopes.
Range Alaska and Yukon south to central California, e. Nevada, and New Mexico (but absent from Oregon), and east to eastern edge of Rockies and Ontario, n. Wisconsin, n. Michigan, Quebec, and Gaspe Peninsula.
Discussion The Chryxus has the broadest tolerances of any arctic, dwelling in a wide array of habitats. Some cut-off populations, such as the ones of the Olympic Mountains of Washington and the northern Sierra Nevada, have become physically distinctive. Its absence from Oregon may be due to recent volcanic activity in the southern Cascade Mountains. The related Sentinel Arctic (O. excubitor) flies on lower slopes in Alaska, the Northwest Territories, and the Yukon. It has 2 eyespots on its hindwing outer angle above.
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