Colias scudderii
Reakirt, 1865
Scudder's Sulphur, willow sulphur
Colias scudderii, commonly known as Scudder's Sulphur or the willow sulphur, is a in the Pieridae. It inhabits mountain meadows and willow bogs across a broad elevational range from Alaska through the Rocky Mountains to northern New Mexico. The has a wingspan of 38–51 mm and is active during summer months. Larvae feed exclusively on willow species (Salix), with later instars .



Pronunciation
How to pronounce Colias scudderii: //ˈkoʊliæs skʌˈdɛraɪ.iː//
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Identification
Distinguished from other North American Colias by its restricted high-elevation in willow bogs and mountain meadows, combined with its geographic distribution from Alaska through the Rocky Mountains. The specific association with Salix plants helps separate it from sympatric sulphurs with different larval requirements.
Images
Habitat
Mountain meadows and willow bogs. Occupies high-elevation environments throughout its range.
Distribution
From Alaska south through the Rocky Mountains to northern New Mexico. Documented from Colorado, Utah, New Mexico, and Wyoming.
Seasonality
active from June to August.
Diet
feed on flower nectar. Larvae feed on leaves of Salix , specifically Salix reticulata, Salix lutea, and Salix planifolia.
Host Associations
- Salix reticulata - larval
- Salix lutea - larval
- Salix planifolia - larval
Life Cycle
laid on willow leaves. Larvae develop through multiple instars; second, third, and fourth instars hibernate. and occur in early summer.
Ecological Role
nectar-feeding contributes to pollination of montane flowering plants. Larval herbivory on willows represents a specialized trophic interaction in subalpine and alpine wetland .
Human Relevance
Subject of entomological study due to its restricted and specialized . No significant agricultural or economic impact documented.
Similar Taxa
- Colias behriiBoth are montane North American sulphurs with restricted ranges; C. behrii occurs in the Sierra Nevada and has different plant associations.
- Colias eurythemeWidespread lowland sulphur that overlaps in range but occupies different (alfalfa fields, agricultural areas) and has broader larval range.
More Details
Subspecies
Two recognized: Colias scudderii scudderii (Colorado, Utah, New Mexico, Wyoming) and Colias scudderii ruckesi Klots, 1937 (New Mexico).
Sources and further reading
- BugGuide
- Wikipedia
- iNaturalist taxon
- NCBI Taxonomy
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