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Colias alexandra Fabricius, 1807
Alexandra's Sulphur
Family: Pieridae (Whites, Marbles, and Sulphurs)
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 #4986)

Map

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Distribution of Colias alexandra 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

Male Alexandra's Sulphurs are yellow, occasionally with orange patches, and have narrow to moderately wide black wing margins. Males reflect ultraviolet light from the outer half of the dorsal hindwing. In normal light this area usually has a deeper yellow tint, occasionally deepening to orange, than the base of the hindwings. Females are white to yellow, with no black border or only faded remnants of the black border. The ventral hindwing is dark greenish. Both sexes usually have a pink ring around the ventral hindwing discal cell spot, and the dorsal hindwing discal cell spot is orange. In 5-10% of individuals, the discal cell spot on the dorsal hindwing is yellow and barely distinguishable from the ground colour, and on the ventral hindwing it is white and lacks a red ring. This is similar to subspecies edwardsii W.H. Edwards, 1870, which occurs in southern Washington.

Immature Stages

Eggs of subspecies alexandra (Colorado) are conical and have 18-20 vertical ribs. They are pale yellow green, turning pink within 48 hours if fertile. First instar larvae are whitish, turning green with a black head once feeding commences. Mature larvae are yellow green, with small black tubercles, a white lateral band with a line of red orange dashes through it, and a green head. Pupae are yellow green with lighter lines that mimic leaf highlights, and three small reddish spots on the ventral side of the abdomen next to the wing (Edwards 1868-72, 1887).

Subspecies

Subspecies columbiensis Ferris, 1973 (TL: Anderson Lake, D'Arcy, BC) occurs only in the Chilcotin District of BC, from D'Arcy in the south to Riske Creek in the north. Males are lemon yellow, with the ultraviolet-reflective areas of the outer hindwing deep yellow. Females are always cream white, with only a hint of a grey wing border. Across the remainder of the Southern Interior and the Kootenays is a new subspecies, found also in northeastern Washington and northern Idaho, which is characterized by a geographic difference in female coloration. This difference in female coloration within BC was noted as long ago as 1950 by Hovanitz, but was missed by Ferris (1973a) because he included in error two yellow female C. gigantea as paratypes for columbiensis (N.G. Kondla, pers. comm.; Fig. 6c of Ferris [1973a]).

Colias alexandra pseudocolumbiensis Guppy & Shepard, new subspecies. C. a. pseudocolumbiensis males are similar to those of columbiensis. On the average they are slightly darker yellow and have a slightly wider black wing border than columbiensis. The outer part of the hindwing is sometimes orange-tinted, which never occurs in columbiensis. Females are distinctly different from those of columbiensis, ranging from nearly as yellow as the males to pale yellow, but almost never the cream white of columbiensis. Females have grey wing borders that vary from barely present to well developed. Types. Holotype: male, BC, Hall Creek at Hwy. 33, 19 July 1986, J. and S. Shepard; a label "HOLOTYPE / Colias alexandra / pseudocolumbiensis / Guppy & Shepard" is attached. The holotype is deposited in the Royal British Columbia Museum, Victoria, BC, CAN. Paratypes: 11 males, 2 females, BC, Hall Creek at Hwy 33, 19 July 1986, J. and S. Shepard (JHS); 6 males, BC, Christian Valley, 13 mi. south, 22 June 1966, J. and S. Shepard (JHS); 2 males, 1 female, BC, Joe Rich Creek, 27 km E of Kelowna on Hwy 33, 13 June and 17 June 1983, C.S. Guppy (CSG).

Genus Description


Colias is the name of a promontory on the coast of Attica where there was a tem pie of Aphrodite. There is no obvious relationship to the butterfly, but the name may be a pun (Emmet 1991). An alternative explanation is suggested under Pontia. The common name "sulphurs" is derived from the yellow "sulphur" colour of most species.

Sulphurs in BC are generally medium-sized butterflies that are yellow, orange, white, or (one species) yellow green with black markings. The wings of males always have a solid black border, with the exception of the Arctic Sulphur. The black borders of females contain extensive pale areas, or may be greatly reduced or absent. There are several multivoltine species that show considerable seasonal variation in wing colour.

There are about 70 species of Colias in the world. The centre of distribution in North America is BC, with more species (13) than any other province or state. Colias species may all be inter-fertile, with natural hybrids known for most species combinations where they occur together in the wild. The species have behavioural, ecological, and physiological differences that maintain separation of the species in the wild (Hovanitz 1963).

Eggs are laid singly on the leaves of the foodplants, and are pale yellow green to cream, later turning orange. Young larvae are slender, yellowish or green, and smooth-skinned with a thin coat of fine hairs. Mature larvae are yellow green or green with fine black dots all over, and stripes of various colours running along the back and sides. Sulphurs hibernate as second to fourth instar larvae (except Canadian Sulphurs, which hibernate as fifth instar larvae), and then complete development in the spring. There are five larval instars in all Colias (Ae 1958a). Pupae are fastened head up with a girdle around the middle.

Members of the genus utilize a wide range of foodplants, although each species specializes to a greater or lesser extent. Larvae of sulphurs feed on plants in three groups: legumes (Fabaceae), Vaccinium (Ericaceae), and Salix (Salicaceae). Sulphurs occur in a wide range of habitats, including arid sagebrush areas, alfalfa fields, meadows, alpine tundra, and forest bogs.

Sulphurs always rest with their wings folded over their backs, and bask in the sun by leaning to the side to allow the sun to warm the underside of their wings. It has been demonstrated for several species (C. meadii, C. nastes, C. philodice, and C. eurytheme) that the darker the pigmentation on the underside of the wings, the more heat can be absorbed from the sun while basking, permitting greater flight activity in cold environments (Kingsolver 1985).

There is relatively little variation in wing pattern between many species, making identification difficult. The key characters mentioned in the species discussions are shown in the figure.

Biology


In BC Alexandra's Sulphurs are in flight from June to August, depending on elevation. Males emerge earlier than females (Watt et al. 1977), as with most butterflies. Females can lay up to 600 eggs, which are laid singly on the upperside of foodplant leaves. A reduction in the number of eggs laid due to inclement weather or adult mortality can strongly affect the population size the next year. Larvae feed on the foodplant leaves, and in subspecies alexandra hibernate in the third instar (Edwards 1887; Ae 1958a), possibly because the larval foodplants dry up before larvae can mature (Ellis 1974). Late third instar larvae stop feeding after about seven days, and move to an untouched leaf or to a neighbouring plant. The larvae are sluggish, somewhat swollen, and lighter green in colour with a relatively small dark green head. The diapause larvae either fall to the ground with the dead plant foliage or crawl into the litter on the ground, where they hibernate. In spring, diapause is broken when the new growth of the foodplant is available for food (Hayes 1981). When more than one egg is laid on a plant, only one larva successfully matures; the rest are dislodged during encounters between larvae or are eliminated through cannibalism (Hayes 1981). Most populations are univoltine, but isolated bivoltine populations occur in Colorado (Ellis 1974; Hayes 1981) and they are bivoltine in Alberta (Bird et al. 1995). Adults are highly mobile and fly long distances, resulting in populations being thinly dispersed over large areas. In Colorado they move an average of 1.3 km, with a maximum recorded dispersal of 8 km, and average about 2 adults per hectare (Watt et al.1977).The larval foodplants tend to be weedy "pioneer" species, and disturbance such as selection logging or ground fires may increase the populations of larval foodplants and therefore of the butterfly. Population size and dispersal rates may also be affected by the availability of nectar sources in their dry environment (Ellis 1974).

Outside BC recorded foodplants are in the family Fabaceae, including Astragalus bisulcatus, A. canadensis, A. eremiticus complex, A. lentiginosus, A. miser, A. robbinsii, Lathyrus lanzwetii var. leucantus, Oxytropis lambertii, Thermopsis pinetorum, and Thermopsis rhombifolia var. divaricarpa (Shields et al. 1970; Ellis 1974; Watt et al. 1977; Hayes 1981).

Habitat


Alexandra's Sulphurs occur in the dry Southern and Central Interior of BC, east of the Cascade and Coast ranges at low and mid elevations. They inhabit dry open pine and fir forests, occurring in grasslands only when dry open forest areas are nearby.

Distribution

Distribution

Alexandra's Sulphurs occur throughout the dry interior areas of montane western North America, from central BC and southern AB south to CA and NM.

Status Information

Scientific NameOrigin StatusProvincial StatusBC List
(Red Blue List)		COSEWIC
Colias alexandraNativeS5YellowNot Listed
Colias alexandra columbiensisNativeS4YellowNot Listed
Colias alexandra pseudocolumbiensisNativeS5YellowNot Listed



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