Bug FAQScudder's Sulphur
Colias scudderi · Order: Lepidoptera · Family: Pieridae
Also called: Willow Sulphur
The willow sulphur butterfly (Colias scudderii) belongs to the Pieridae family and has a wingspan of about 38 to 51 mm. Adults feed on flower nectar, while the larvae eat willow (Salix) leaves and the later instars hibernate over winter.
Source: Wikipedia
How to recognize it
Colias scudderii, called the willow sulphur, belongs to the butterfly family Pieridae.
Source: Wikipedia
Size
Its wingspan ranges from about 38 to 51 millimetres (1.5 to 2 inches).
Source: Wikipedia
Where it lives
It lives in mountain meadows and willow bogs.
Source: Wikipedia
What it eats
Adults sip nectar from flowers. The caterpillars eat leaves of willow (Salix) species.
Source: Wikipedia
Life cycle
Later-instar larvae (second to fourth) spend the winter in hibernation.
Source: Wikipedia
When you see it
Adults are on the wing from June through August.
Source: Wikipedia
Where it comes from
It is native from Alaska, through the Rocky Mountains, down to northern New Mexico.
Source: Wikipedia
Where it is found in the US
Recorded in 9 of 51 states and DC. Most records: Colorado, Wyoming, Utah, New Mexico, Idaho, Alaska, Montana, California.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in United States. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
What do the caterpillars eat?
The larvae feed on the leaves of willow (Salix) plants.
Source: Wikipedia
Where does this butterfly live?
It inhabits mountain meadows and willow bogs in Alaska, the Rocky Mountains, and northern New Mexico.
Source: Wikipedia
How large is the willow sulphur?
Its wingspan measures about 38 to 51 mm (1.5 to 2 in).
Source: Wikipedia
Same family (Pieridae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Colias_scudderii
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.