Western Pygmy-Blue
Brephidium exile
Description
3/8-3/4" (10-19 mm). Tiny. Bicolored above; white-fringed chocolate-brown with ultramarine blue inward, female larger than male and less blue. Below, gray-brown blending to bluish-gray at base; tiny iridescent blue-green centered
black spots on HW margin; white striations across wings.
Similar Species
Eastern Pygmy-blue fringes darker, bases of wings brownish below; ranges usually do not overlap.
Life Cycle
Egg aquamarine. Caterpillar pale green to cream-white, with yellow stripes on back and sides, and tiny brown bumps overall; feeds on plants of goosefoot family, including pickleweed (Salicornia ambigua), saltbush (Atriplex), and pigweed (Chenopodium).
Flight
Continuous broods in S. Texas and California, peaking in late summer and autumn.
Habitat
Lowland, often disturbed places and coastlines: washes, marshes, alkali flats, railroad tracks, and vacant lots.
Range
E. Oregon, California, and Great Basin south to Texas and South America, east to Nebraska and other plains states.
Discussion
This smallest western butterfly is often abundant, but nevertheless usually passes unnoticed because of its diminutive size and slow flight. Despite its minuteness and seeming fragility, the Western Pygmy-blue emigrates northward each year from its year-round southern homeland. Northern records probably represent these emigrants and their summer offspring rather than resident colonies.
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