Dusky Azure
Celastrina nigra
Description
3/4-1 1/4" (19-32 mm). Above, male blackish-brown, with occasional blue scaling at wing bases; female lustrous, pale gray-blue, black-bordered, with extensive whitish suffusion. Below, both sexes pale ash-colored to bluish-white, HW irregularly black dotted, with dusky marginal spots large and distinct along entire border.
Similar Species
Spring Azure similar below but much bluer above. Female Eastern Tailed Blue has tails and orange spots.
Life Cycle
Egg greenish, ribbed. mature caterpillar uniform whitish blue-green, faintly yellow tiger-striped (not checkered like Spring Azure); feeds on goat's beard (Aruncus dioicus). Chrysalis brown, flecked black; overwinters.
Flight
1 brood; April-early May.
Habitat
Rich, moist, deciduous forests, especially shaded northern slopes where goat's beard grows.
Range
Illinois and W. Pennsylvania south to Missouri and North Carolina.
Discussion
Only recently distinguished from the widespread Spring Azure, with which it flies, the Dusky Azure is much rarer and more local. These blues imbibe moisture from damp sand and dew and may take nectar at violet and geranium flowers. In most blues the male is blue and the female grayer; the Dusky Azure reverses this pattern.
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