|scientific name Celastrina ladon nigrescens |
common name Western Spring Azure
In Alberta, found only in montane meadows in the Castle River - Waterton region.
One brood, emerging in May to early June.
The Western Spring Azure lacks any trace of orange markings on the underside, and has a white-grey underside with black median and marginal dots. Very similar to the Boreal Spring Azure (C. ladon lucia), but in Alberta these two occur together only in the Castle River - Waterton Lakes region. The underside ground colour of nigrescens is lighter than lucia, and the upperside of males is violet-blue, not pale powder-blue as in lucia. Individuals of both species occasionally occur that have coalescent hindwing spots, resulting in a large blotch rather than a number of dots.
The taxonomy of this group of species has been very confusing, and research is still ongoing to define the number of species and the appropriate names for this genus in North America; nigrescens and lucia do not intergrade but remain distinct where they occur together in BC and Alberta (Bird et al. 1995, Guppy & Shepard 2001, Schmidt unpubl. data), evidence that they are separate species rather than geographic forms of the same species.
No data available for Alberta. On the west coast of BC, the eggs are white, and shaped like a slightly flattened sphere; mature larvae come in a variety of colours: green, purplish (Guppy & Shepard 2001) or white to pale pink with a transverse bar on the first abdominal segment (Ballmer & Pratt 1989). Tatum (2002) provides excellent photographs of pale yellow and wine-colored larvae and a mottled-brown pupa from Vancouver Island.
Scott (1992) noted that although larvae can feed on a wide variety of flowers, females lay eggs on only a particular stage of the flower bud, and then only on species with a clustered flower structure, likely to ensure the larva has enough food to fully develop without having to relocate.
The Western Spring Azure is restricted to a small geographic area in Alberta.
No Alberta data. In BC, larvae feed on the flowers and developing seeds of ocean spray (Holodiscus discolor), Ceanothus (Ceanothus sp.) and hardhack (Spiraea douglasii) (Guppy & Shepard 2001). Of these, only Ceanothus velutinus occurs in Alberta (Moss 1992).
Southern BC and extreme southwestern Alberta south to Baja California (Bird et al. 1995, Guppy & Shepard 2001, Pratt et al. 1994).
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