Colias nastes

Boisduval, 1832

Labrador Sulphur, Labrador sulfur

Colias nastes is a high-latitude sulphur in the Pieridae, commonly known as the Labrador Sulphur. It occurs across the Holarctic region, with in Arctic and alpine zones of North America, northern Europe, and Asia. The exhibits pronounced melanism, with darker individuals showing greater activity in cool conditions. Larvae feed primarily on Astragalus species.

Colias nastes by the Smithsonian. Used under a CC0 license.

Colias nastes thula by the Smithsonian. Used under a CC0 license.

Pronunciation

How to pronounce Colias nastes: /ˈkoʊliæs ˈnæstiːz/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from other Colias by dark grey-green coloration with red fringes; females more yellowish with yellow submarginal spots. Underside pattern with white spot bordered red on hindwing and diffuse red spot distally. Smaller than many ; high-latitude distribution also diagnostic.

Images

Appearance

Wingspan 31–45 mm. surface dark grey-green with grey-black margins and red fringes. Female more yellowish with distinct yellowish submarginal spots on both wings. Underside of forewing impure whitish with greenish-yellow ; rose-red fringes conspicuous. Hindwing yellowish-green, lighter at margin, with white spot bordered with red and diffuse red spot distally; rose-red fringes broader than on forewing. Female underside somewhat lighter; forewing with small black submarginal spots.

Habitat

Arctic and alpine zones. In North America, occurs in tundra and alpine meadows of Alaska, Canada, Rocky Mountains, and Greenland. In Europe, northern Scandinavia. In Asia, Altai Mountains, Sayan Mountains, northern Siberia, and Chukotka.

Distribution

Holarctic. North America: Alaska, Canada (Yukon, Northwest Territories, British Columbia, Alberta, Manitoba, Labrador), Greenland, Rocky Mountains (Washington, Montana). Europe: northern Norway, northern Sweden, rare in northern Finland. Asia: Altai Mountains, Sayan Mountains, northern Siberia, Chukotka, border regions of Russia, China, Mongolia, Kazakhstan.

Seasonality

fly May to August depending on location.

Diet

Larvae feed on Astragalus , especially A. alpinus and A. frigidus. In North America also recorded on Trifolium repens and possibly Vaccinium species.

Life Cycle

stage not explicitly documented in sources. Complete with , larva, pupa, and stages.

Behavior

Darker, more melanistic individuals remain active under cooler or cloudier conditions and move greater distances than lighter individuals. Lighter individuals suffer greater than dark individuals, but only at higher elevations. Higher disappearance rates of darker individuals from are not attributable to increased predation.

Ecological Role

. Larvae are herbivores feeding on leguminous plants.

Human Relevance

Minor agricultural pest in North America where larvae occasionally feed on Trifolium repens (white clover). Subject of research on melanism and thermal in Arctic-alpine insects.

Similar Taxa

Colias eurythemeOrange sulphur is more yellow to orange, lacks dark grey-green coloration and red fringes; occurs at lower elevations and latitudes in more temperate regions.
Colias behriiBehr's sulphur is restricted to Sierra Nevada of California; differs in and distribution with no range overlap.

More Details

Melanism and Climate Adaptation

Geographic patterns of increased melanism in Arctic and alpine Colias butterflies represent evolutionary responses to consistently colder temperatures rather than local variation in pressure.

Subspecies

Numerous recognized reflecting broad geographic range: C. n. nastes (Altai, Sayan, Chukot Peninsula, Alaska, Greenland, Labrador), C. n. aliaska (Alaska, Yukon, Northwest Territories), C. n. streckeri (Alberta, British Columbia, Washington, Montana), C. n. moina (Northwest Territories, Manitoba), and others described from 2021 from British Columbia, Yukon, and adjacent regions.