Pink-edged Sulphur

S1

Pink-edged Sulphur

Scientific Name

(Colias interior)

The Pink-edged Sulphur is a medium- size butterfly in the Pieridae family (1). They range from western Canada and eastern Oregon, through the Great Lakes region to northern New England, southward through Pennsylvania, eastern West Virginia, and northwest Virginia (2). In Maryland, the species is only known from high elevations of the Allegheny Plateau in Garrett Co. and it has a state rank of S1, highly state rare (3, 4).

Photo by ©Jay CosseyPhotographsFromNature.com (PFN)

Photo by Aaron Brees

Identification

The Pink-edged Sulphur has a wingspan of 1 ½ to 2 ⅝ inches (2) and is named for the pink fringe on the edge of their wings (5). Males have black borders on the upperside of their outer wing, while females have a faded black border on the forewing apex (5). Their underside is mostly pale greenish-yellow with a hollow dot on each wing (5).

This butterfly can be easily confused by the Orange Sulphur (Colias eurytheme) which has an orange tint on the uppersides, and the Clouded Sulphur (Colias philodice), which has faint black dots along the submarginal area of their ventral wings. Both of the latter species are common in Maryland (3).

The Orange Sulphur

Photo by Cody Hough, college student and photographer in the Michgian area.

The Clouded Sulphur

Photo by U.S. Fish and Wildlife Service Northeast Region

Life Cycle

Females lay eggs midsummer on the larval host plants, Lowbush Blueberry and Velvetleaf Blueberry (Vaccinium myrtilloides) (2, 3, 4, 6). In Maryland, Velvetleaf Blueberry is a vulnerable species, with a rank of S1 (3).

Photo by MJ Springett Wildlife Photography

Adults have one flight period from July to early August and hibernate during their third instar (6, 7). They tend to visit non-native Red Clover (Trifolium pratense) and Heal-all (Prunella vulgaris) also known as Common Selfheal (3, 4). Males can be found awaiting females with a slow flight (2).

Habitat

The Pink-edged Sulphur can be found in bogs with blueberry or shrubland habitat (4). They prefer Lowbush Blueberry and Velvetleaf Blueberry where they will spend their days feeding as caterpillars (4, 6).

Larval Host Plants

Lowbush Blueberry

Photo by Jim BrightonRetrieved from Maryland Biodiversity Project

Velvetleaf Blueberry

Photo by Jim Stasz

Adult Host Plants

Red Clover

Photo by Sanja565658. Retrieved from Wikimedia Commons License: CC BY-SA 3.0

Common Selfheal

Photo by Jesse Taylor. Retrieved from Wikimedia Commons License: CC BY-SA 3.0

Distribution in Maryland

Data from Maryland Biodiversity Project. Includes historical data and may overrepresent the current range of the species.

Distribution in US

Data from Butterflies and Moths of North America

How can you help?

Understanding and becoming aware of the Pink-edged Sulphurs' habitat is necessary for their survival (5). This species is currently under review and the state rank will likely be changed to extirpated (personal comm. Jennifer Selfridge).

References

Karowe, D. N. 1988. Ecological and evolutionary determinant of larval host plant range in the sulfur butterflies, Colias philodice and Colias interior. Doctoral Dissertation available at The University of Michigan. https://deepblue.lib.umich.edu/handle/2027.42/128158?show=full
Colias interior, Pink-edged Sulphur. BugGuide.net. Iowa State University, Department of Entomology. https://bugguide.net/node/view/27641. Last accessed 10 September 2020.
Maryland Biodiversity Project. Pink-edged Sulphur Colias interior Scudder, 1862 https://www.marylandbiodiversity.com/view/501. Last accessed 10 September 2020.
Davis, L. and R. Smith. 2014. Butterflies of Maryland: A biological checklist. Maryland Department of Natural Resources, Wildlife and Heritage Division. https://dnr.maryland.gov/wildlife/Documents/butterfliesofmaryland_biological-summary_checklist.pdf
Virginia Department of Conservation and Recreation. Atlas of rare Butterflies, Skippers, Moths, Dragonflies & Damselflies of Virginia. Last accessed 13 September 2020.
Karowe, D. N. 1994. Diapause dynamics and host plant utilization of Colias philodice, Colias interior and their hybrids (Lepidoptera: Pieridae). The Great Lakes Entomologist 27(2): 79-88.
A. E., Shigeru Albert. 1958. Comparative studies of developmental rates, hibernation, and food plants in North American Colias (Lepidoptera, Pieridae). The American Midland Naturalist 60(1): 84-96.

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