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Plebejus icarioides montis Nabokov, 1944
Boisduval's Blue
Family: Lycaenidae (Gossamer Wings)
Species account authors: Crispin Guppy and Jon Shepard.
Extracted from Butterflies of British Columbia.
Introduction to the Lepidoptera of BC
Introduction to the Butterflies of BC
The Families of Lepidoptera of BC

Photograph

© Norbert Kondla     (Photo ID #5448)

Map

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Distribution of Plebejus icarioides montis in British Columbia.
(Click on the map to view a larger version.)
Source: Butterflies of British Columbia by Crispin Guppy and Jon Shepard © Royal BC Museum

Species Information


Adult

Boisduval's Blue is difficult to characterize. The blue on the upperside of the male wing is not clear but somewhat washed out. The male underside is brown, heavily overlaid with white scales that give it the appearance of the underside of the Sooty Hairstreak, which is not blue on the upperside. The female upperside is brown, with usually a flush of blue scales at the base of the forewing. The ground colour of the female underside is brown. For Vancouver Island individuals, the female ventral hindwing has a median row of white spots. For mainland populations, these spots are large with small black centres. The ventral forewing of Vancouver Island females has a median row of black spots surrounded by white scales. These spots are much larger in mainland populations.

Immature Stages

Comstock and Dammers (1935) described the egg as green overlaid by the white papillae of the chorion. The mature larva is green with three inconspicuous diagonal white lines laterally on each body segment. The body is covered with short white hairs. The pupa is green on the head, thorax, and wings, and chestnut red with green spots on the abdomen.

Subspecies

Vancouver Island populations are the subspecies I.i. blackmorei (Barnes & McDunnough, 1919) (TL: Goldstream, BC). Populations from the southern Coast Range and the adjacent Cascades are I.i. montis (Blackmore, 1923) (TL: Mt. McLean, near Lillooet, BC). Populations from the Okanagan Valley eastward are the Rocky Mountain subspecies, I.i. pembina (W.H. Edwards, 1862) (TL: Ravilli Co., MT).

Genus Description


When Nabokov (1944) coined this generic name, he said it was allied to the European genus Aricia Rechenbach, 1817. Considering Nabokov's love of word games, the generic name lcaricia is a play on that relationship and the name of the type species, icarioides.

The labides of the male genitalia is stout and often toothed. The falces is short, poorly sclerotized, and often inconspicuous. The dorsal tip of the valve is elongate and enlarged except in the species lcaricia shasta (W.H. Edwards, 1862), which does not occur in our fauna.

This Nearctic genus contains five species. Two occur in BC. Larvae feed on either Fabaceae or Polygonaceae.

Biology


Boisduval's Blue is univoltine and flies from mid-May at lower elevations to mid-August at higher elevations, but only for a month at anyone locality in anyone season. Newcomer (1911) partially described the life history of the California Sierran subspecies. Eggs are laid in equal numbers on leaves and seed pods of lupines. The eggs hatch within 10 days and develop into mature second instar larvae before hibernating. Newcomer (1911) also mentioned collecting a mature larva in August, apparently from lower elevation; it pupated in late August and emerged the following spring. Comstock and Dammers (1935) reared the southern California mountain subspecies and found that it also overwintered as mature second instar larvae. They observed pupation at the base of the larval foodplant, Lupinus sp. The pupal stage lasted three weeks before the adults emerged. Downey (1962a) documented extensive myrmecophily, or ant attendance, upon Boisduval's Blue larvae. He recorded 11 species of ants from six genera, and often two ant species for one population of Boisduval's Blue. Downey (1962b) recorded the genus Trichogramma (Hymenoptera: Trichogrammatidae) as an egg parasitoid from 50% of the 53 populations studied. He also recorded one instance of larval parasitism by Apanteles theclae Riley (Hymenoptera: Braconidae). Newcomer (1911) noted tachinid fly eggs on the larvae but did not rear them to maturity. Boisduval's Blue has been recorded feeding as larvae on 38 species or varieties of lupines across western North America, but for anyone population of Boisduval's Blue, only one type of lupine is used for oviposition (Downey and Fuller 1961; Downey and Dunn 1964). Barnes and McDunnough (1919) reported that Blackmore associated Boisduval's Blue with Lupinus arcticus.

Habitat


Boisduval's Blue occurs across southern BC wherever Lupinus spp., especially hair-leafed species, occur. Low-elevation Vancouver Island populations have not been seen since the 1960s. Most likely the spread of Scotch broom and fire suppression choked out the native lupine, Lupinus latifolius, on which the larvae feed. Subalpine clearcut logging has opened up more habitat for new lupine growth, however, and the butterfly is currently flourishing in some subalpine areas.

Distribution

Distribution

Boisduval's Blue is found from southern BC to southern SK and south to Baja California and northern MEX.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)		COSEWIC
NativeS4YellowNot Listed



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