Bug FAQLabrador Sulphur
Colias nastes · Order: Lepidoptera · Family: Pieridae
Also called: Nastes Sulphur, Pale Arctic Clouded Yellow
It occurs in northern Europe (Norway, Sweden, occasional northern Finland) and across North America from Alaska and Canada to the Rocky Mountains, Washington, Montana and Greenland. Adults fly from May to August, varying with location.
Source: Wikipedia
How to recognize it
The butterfly is dark grey-green with grey-black wing margins and red fringes. Females are more yellowish and show clearer yellow submarginal spots on both wings.
Source: Wikipedia
Size
Wingspan ranges from 31 to 45 mm.
Source: Wikipedia
Where it lives
In Europe it lives in the far north of Norway and Sweden and is rarely seen in northern Finland. In North America it is found in Alaska, Canada, the Rocky Mountains, Washington, Montana and Greenland.
Source: Wikipedia
What it eats
In North America they have also been recorded on white clover (Trifolium repens) and possibly on Vaccinium species.
Source: Wikipedia
Life cycle
Adults are on the wing from May through August, depending on the locality.
Source: Wikipedia
When you see it
Flight period spans May to August, varying with location.
Source: Wikipedia
Where it comes from
Its European range includes northern Norway and Sweden, with occasional records from northern Finland. In North America it is native to Alaska, Canada, the Rocky Mountains, Washington, Montana and Greenland.
Source: Wikipedia
Where it is found in the US
Recorded in 3 of 51 states and DC. Most records: Alaska, Washington, Montana.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in Canada; native in United States. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
When are Labrador sulphur butterflies active?
Adults fly from May to August, with exact timing depending on where they live.
Source: Wikipedia
Same family (Pieridae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Colias_nastes
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-24 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-24.