Spring Azure (Celastrina ladon) (Cramer, )
Diagnosis: This species is part of a complex of closely related species that is currently under study in North America (see Remarks below). The upper surface is pale blue (purplish blue in western Canada), with a broad blackish-grey border on the outer quarter of the forewing in females. The underside is pale brownish grey with dark grey spots and a zigzagged submarginal line on the hindwing (form "violacea"). In most of Canada there is also dark grey shading along the margin of the hindwing (form "marginata"), or in the middle of the hindwing connecting many of the central spots (form "lucia"), or in both areas. Wingspan: 18 to 28 mm.
Subspecies: Subspecies lucia, which occurs in most of Canada, is pale blue above and has dark grey marginal or central patches on the hindwing below. The nominate subspecies ladon (Cramer) occurs through the eastern U.S. and has no dark grey patches below (i.e., form "violacea"); forms resembling both subspecies occur in a blend zone between the two subspecies in southeastern Canada and the northeastern U.S. Subspecies nigrescens occurs in southwestern Alberta and southern British Columbia as far west as the Okanagan Valley; males are darker purplish blue above and females have extensive grey shading on the outer half of the forewing and varying amounts on the hindwing; the underside is pale grey brown and both "violacea" and "lucia" forms are common. Subspecies echo in southwestern British Columbia is similar to subspecies nigrescens, but the underside is paler grey and form "lucia" is very rare.
Range: The Spring Azure occurs throughout Canada as far north as treeline.
Similar Species: The Summer Azure (C. neglecta) is larger, has white shading over the blue, especially on the hindwing, and is white or very pale grey underneath with tiny dark spots; it flies later than the Spring Azure, usually between mid-June and early September. The Cherry Gall Azure (Celastrina sp.) is very similar to the Spring Azure above and below, but tends to be a little paler and flies in late May and June after the flight of the Spring Azure. [compare images]
Early Stages: Eggs are laid singly on flower buds; the larvae eat flowers and developing fruits and are tended by ants. The larva is most commonly green but also may be yellowish brown or reddish brown with a darker middorsal stripe. It hibernates as a pupa with the adult emerging in the early spring. The larvae feed on a wide variety of usually white-flowering trees and shrubs. Favoured foodplants in Canada are cherry (Prunus spp.), blueberry (Vaccinium spp.), and early blooming viburnums (Viburnum spp.).
Abundance: The Spring Azure is fairly common in most of its Canadian range, though never occurring in large numbers. It is uncommon to rare in southern Ontario where it is more confined to rich deciduous woods than farther north.
Flight Season: Adults are on the wing from early April to mid-May in southern Ontario and from late April to mid-June in the rest of its Canadian range, generally flying later in the far north and in cooler maritime areas than elsewhere.
Habits: Adults are most commonly seen in open woodlands and along woodland margins where flowering shrubs are common.
Remarks: Recent and ongoing studies of the Spring Azure complex (e.g., Pratt et al., 1994; Wright, 1995) have revealed as many as six species confused under this name. We discuss three that are known to occur in Canada. Two others, the Appalachian Azure (C. neglectamajor Tutt) and Edwards' Azure (C. violacea (W.H. Edwards)) occur as far north as the southern shore of Lake Erie and may occur in southern Ontario. They are likely to be discovered only by foodplant association; they feed on Black Cohosh (Cimifuga recemosa) and Flowering Dogwood (Cornus florida), respectively. The Spring Azure has been treated as the same species as the Holly Blue (C. argiolus (Linnaeus)) of Eurasia, but this needs to be demonstrated in view of differences in appearance and habits.
© 2002. This material is reproduced with permission from The Butterflies of Canada by Ross A. Layberry, Peter W. Hall, and J. Donald Lafontaine. University of Toronto Press; 1998. Specimen photos courtesy of John T. Fowler.
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