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Montana Field Guide

Montana Field Guides

Margined White - Pieris marginalis

Native Species

Global Rank: G5
State Rank: S5

Agency Status


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General Description
[From Ferris and Brown 1981; Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002] Forewing 2.0-2.5 cm. White overall, forewing somewhat pointed. Uppersurface immaculate white to heavily dusted with black, black scaling concentrated along wing veins, nearly absent in cells between veins. Male sometimes with a single round black spot in discal cell of forewing, female sometimes with two black spots (one in discal cell, one near trailing edge of wing more diffuse). Undersurface nearly immaculate white to yellow-tinged, heavily marked with gray-green along veins.

One flight, mostly June in Alaska and in the Rocky Mountain states; two or three flights elsewhere, February to mid-September (Scott 1986). June to mid-August in most of range, April to August in Arizona and New Mexico, mostly May to July in Pacific lowlands (Glassberg 2001). Early April to early October, depending on elevation in Colorado (Scott and Scott 1978), early March to early October in Oregon and Washington (Pyle 2002), early March to mid-September in Oregon (Warren 2005), late April to September in British Columbia (Threatful 1988; Guppy and Shepard 2001).

Diagnostic Characteristics
Best determined by a combination of uppersurface immaculate white to heavily dusted with black, black scaling concentrated along wing veins and nearly absent in cells between veins; undersurface nearly immaculate white to yellow-tinged, heavily marked with gray-green along veins .

Species Range
Montana Range Range Descriptions


Range Comments
Alaska panhandle and British Columbia south in the west to central California, east to southeastern Montana, western South Dakota and Nebraska, central Colorado, east-central Arizona, and southern New Mexico, with an isolated population in the Cypress Hills of Alberta/Saskatchewan; largely absent from southwestern deserts and arid lands (Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002); 1310 m to 2743 m elevation in Colorado (Scott and Scott 1978), mostly 2743 m elevation to treeline in Colorado (Brown 1957), above 2135 m elevation in the central Rocky Mountains (Ferris and Brown 1981), sea level to over 1829 m elevation in Oregon (Warren 2005), to at least 2134 m elevation in Washington (James and Nunnallee 2011), 456 m to 1859 m elevation in southeastern British Columbia (Threatful 1988). In Montana, reported from all counties in the western 1/2 of the state, east to Custer County (Kohler 1980; Stanford and Opler 1993). Uncommon to common (Glassberg 2001).

Observations in Montana Natural Heritage Program Database
Number of Observations: 36

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Non-migratory; adults may move up to 5 km (Scott 1986).

Moist woods and meadows, coniferous forest openings, along stream courses, roadsides, glens, seeps, tundra (Scott 1986; Opler and Wright 1999; Glassberg 2001; Pyle 2002). In Glacier National Park, Montana reported above treeline in alpine terrain (Debinski 1993); in the Greater Yellowstone Ecosystem reported in shady deciduous and conifer forest, forest clearings and edges, tundra, roadsides, and montane wet meadows (Debinski and Pritchard 2002; Debinski et al. 2013).

Food Habits
Larval food plants are native and exotic mustards, including Alyssum, Arabis, Armoracia, Barbarea, Brassica (multiple species), Cardamine (multiple species), Dentaria, Descurainia, Draba, Lepidium, Nasturtium, Raphanus, Rorippa, Sinapis, Sisymbrium, and Thlaspi (Scott 1986, 1992, 2006; Guppy and Shepard 2001; Graves and Shapiro 2003; James and Nunnallee 2011). Adults feed on flower nectar, including Achillea, Arnica, Arctium, Astragalus, Cardamine, Claytonia, Epilobium, Erigeron, Eriogonum, Fragaria, Geranium, Monarda, Oxypolis, Potentilla, Rubus, Senecio, Smilacina, Solidago, Symphyotrichum, and Taraxacum (Pyle 2002; James and Nunnallee 2011; Scott 2014).

Reproductive Characteristics
Females lay eggs singly, mostly on the undersides of host plant leaves, sometimes stems (Scott 1986, 1992, 2006; James and Nunnallee 2011). Number of eggs per ovariole (1/8 of total) about 90 (Ehrlich and Ehrlich 1978). Eggs hatch in about 4-5 days (depending on temperature), develop rapidly from L1 instar to L5 instar and pupae in about 18-21 days post egg-hatch, adults eclose (emerge from pupae) in about 8-10 days (Guppy and Shepard 2001; James and Nunnallee 2011). Larvae bore into leaves, feed also on flowers and fruits, build no nests, pupate on and off host plant; pupae hibernate (Scott 1979, 1986; Guppy and Shepard 2001; James and Nunnallee 2011). Males patrol throughout the day along trails, roads, shaded watercourses seeking females (Scott 1975b, 1986; James and Nunnallee 2011).

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Citation for data on this website:
Margined White — Pieris marginalis.  Montana Field Guide.  .  Retrieved on , from