Glaucopsyche lygdamus

(Doubleday, 1841)

silvery blue

Glaucopsyche lygdamus, the silvery blue, is a small native to North America. It exhibits in wing coloration, with males displaying light blue uppersides and females showing dull grayish blue. The occupies diverse across western North America and Canada, and has demonstrated significant range expansion in some regions. Multiple have been described, reflecting geographic variation in and .

Glaucopsyche lygdamus by (c) Owen Strickland, some rights reserved (CC BY), uploaded by Owen Strickland. Used under a CC-BY license.

Silvery Blue (Glaucopsyche lygdamus) (8937100711) by Aaron Carlson from Menomonie, WI, USA. Used under a CC BY-SA 2.0 license.

Glaucopsyche lygdamus by Jacy Lucier. Used under a CC BY-SA 4.0 license.

Pronunciation

How to pronounce Glaucopsyche lygdamus: //ˌɡlɔːkəˈsaɪki ˈlɪɡdəməs//

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

Identification

Distinguished from tailed-blue (Cupido comyntas, C. amyntula) by absence of small tail-like projections on hindwings. Differs from Greenish blue (Aricia saepiolus) and Boisduval's blue (Aricia icarioides) by having single rather than double row of spots on underside. Arrowhead blue (Glaucopsyche piasus) is similar but has distinct arrowhead-shaped spots. Spot size on underside varies geographically and can aid in identification.

Images

Appearance

Small with wingspan 18–28 mm. Upperside light blue in males, dull grayish blue in females. Underside gray with single row of round spots; spot size varies regionally. No tail-like projections on hindwings.

Habitat

Occupies diverse including alpine meadows, shale barrens, sand dunes, wooded areas, and alvar woodlands. In southern Ontario, found in both open anthropogenic habitats and undisturbed alvar woodlands. Range expansion in northeastern North America associated with open, disturbed habitats and introduced legumes.

Distribution

Western United States, most of Canada (except most of Nunavut and high Arctic islands). Range expansion documented in northeastern North America since 1940s–1950s, reaching southern Ontario by 2012. Historical in Ottawa Valley and Bruce Peninsula, Ontario.

Diet

feed on nectar. Larvae feed on Lupinus and, in at least one Ontario , native Astragalus neglectus (Neglected Milk-Vetch).

Host Associations

Lupinus - larval food plantprimary
Astragalus neglectus - larval food plantdocumented in eastern Ontario alvar

Life Cycle

Complete . deposited on plants by free-flying females. Larvae feed on host foliage, pupate, and emerge as . Specific developmental timing varies with latitude and elevation.

Behavior

Females oviposit on plants while in . couperi has undergone substantial southward range expansion since mid-20th century, utilizing introduced legumes and open anthropogenic . Non-expanding persist in specialized habitats such as alvar woodlands and sand plains.

Ecological Role

Larval herbivore on leguminous plants. as . Range expansion may be accompanied by increasing loads.

Human Relevance

Subject of conservation concern regarding genetic and phenotypic diversity decline due to range expansion and modification. Closely related to extinct Xerces blue (Glaucopsyche xerces), which serves as emblematic example of extinction due to urban development.

Similar Taxa

Cupido comyntasEastern tailed-blue has small tail-like projections on hindwings absent in G. lygdamus
Cupido amyntulaWestern tailed-blue has small tail-like projections on hindwings absent in G. lygdamus
Aricia saepiolusGreenish blue has two rows of small black spots on underside versus single row in G. lygdamus
Aricia icarioidesBoisduval's blue has two rows of small black spots on underside versus single row in G. lygdamus
Glaucopsyche piasusArrowhead blue has arrowhead-shaped spots rather than round spots

More Details

Subspecies diversity

At least 16 described, including G. l. couperi (northern silvery blue), G. l. palosverdesensis (Palos Verdes blue, endangered), and G. l. xerces (Xerces blue, extinct). Subspecies show variation in spot size, coloration, and association. Some southern Ontario show transitional characters between subspecies.

Range expansion dynamics

couperi expanded from northern Ontario into southern Ontario since 1940s–1950s, reaching Hamilton by 2012. Expansion facilitated by introduced legumes and open . Contrasts with relict in alvar woodlands that may represent early postglacial isolates.