For the Silvery Blue the upperside of the male wing is a "silvery" blue with a narrower black border than the Arrowhead Blue. The ground colour of the upperside of the female wings is brown, with a flush of blue scales at the base. Neither sex has any orange markings. The underside of the Silvery Blue is very diagnostic. The ground colour is a uniform light brown with strongly contrasting black spots bordered by white. There is no mottling or other variation to the uniform ground colour.
Both Bower (1911) in the east and Williams (1908) described the immatures. Bower gave the best account. The egg is turban-shaped. It is green and the white chorion has a reticulated surface. The egg turns white before hatching. The mature larva is light green and covered with a granulated surface of white dots. The dorsal line is dark green, edged with light yellow green. The subspiracular line is conspicuously cream, edged with dark green.
Populations in southern BC are the subspecies G.l. columbia (Skinner, 1917) (TL: Fort Columbia, [Okanogan Co.], WA). Northern populations are the boreal subspecies, G.l. couperi Grote, 1873 (TL: Anticosti Island, PQ). The northern subspecies is smaller.
The name Glaucopsyche is derived from the Greek glaucus (grey blue) and psyche (the soul personified as a butterfly [Emmet 1991]). There does not appear to be a common name for the genus.
The genus Glaucopsyche is structurally similar to the preceding genus, with some genitalic differences. The species are significantly larger in size and lack the red markings of Euphilotes. The larvae feed on plants of the family Fabaceae, especially Lupinus. There are three Nearctic species, including the extinct G. xerxes (Boisduval, 1852) from San Francisco, CA, and three Palearctic species.
The Silvery Blue flies from late April at low elevations to mid-July in subalpine meadows, but not for more than a month at any site, especially at dry, low elevations. Eggs are laid on the foliage of the larval foodplant and the larvae feed externally, attended by ants (Bower 1911). The larvae pupate in July and overwinter in ant nests (Tilden 1947). Bower (1911) states that the entire life cycle from egg laying to pupation takes only 26 days. Dolinger et al. (1973) found that populations of lupines that were intensely fed on by larvae of the Silvery Blue developed very high concentrations of alkaloids, thus discouraging further larval feeding.
After the flight period of the Spring Azure, this species becomes the common late spring to early summer blue throughout BC, except for the west coast of Vancouver Island, the Queen Charlotte Islands, and the North Coast. It is found in virtually any situation where wild legumes are found, from the lowest elevations to near timberline.
The Silvery Blue ranges from western AK south through BC to Baja California and NM, and east to Labrador and NF. In the east it occurs south to the Great Lakes, with disjunct populations in the Ozarks and the Appalachians.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2020-06-01 1:51:21 AM]
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