Page 147 - The Book of Caterpillars: A Life-Size Guide to Six Hundred Species From Around the World
P. 147

BUTTERFLY CATERPILLARS

                      FAMILY  Lycaenidae
                  DISTRIBUTION  Southern and western United States, Mexico, and south
                           to Venezuela

                     HABITAT  Desert flats, gullies, roadsides, weedy areas, and salt marshes
                  HOST PLANTS  Chenopodiaceae, including saltbush (Atriplex spp.),
                           Russian thistle (Salsola spp.), Shoreline Purslane (Sesuvium
                           portulacastrum), and Black Pigweed (Trianthema portulacastrum)

                      NOTE  One of the smallest butterfly caterpillars in the world
             CONSERVATION STATUS  Not evaluated, but secure though possibly rare in parts
                           of its range




                                                                                   ADULT WINGSPAN
                                                                                    ¹∕₁₆ in (18 mm)
                                                                                  CATERPILLAR LENGTH
                                                                                    ⁷∕₁₆ in (11 mm)
            BREPHIDIUM EXILIS
            WESTERN PYGMY BLUE                                                                   145

            (BOISDUVAL, 1852)


            The tiny Western Pygmy Blue caterpillar has numerous stubby
            setae, giving it a frosted appearance. The eggs hatch in four to


            five days, and the emerging caterpillars feed on leaves, flowers,

            and seeds, often hiding in bracts. Concealment and camouflage
            help protect them, as does attendance by ants, which deter     Actual size
            predators and parasitoids. The caterpillars develop rapidly, with
            pupation occurring after about three weeks; the adults emerge
            eight to ten days later. There is no dormancy stage, and breeding
            continues year round in the southern United States and Mexico.


            Because they blend in so well with their surroundings,   The Western Pygmy Blue caterpillar is light
            caterpillars of Western Pygmy Blues are hard to find on host   green with a black, shiny head, and an indistinct,

                                                               ventrolateral, white line and numerous splotchy,
            plants, but the presence of attending ants may provide clues.   white markings laterally. Dorsally, yellowish-white
            The tiny adults are inconspicuous in flight. Males spend much   markings form two lines of small chevrons. A red

                                                               form of the caterpillar also occurs in which the
            time searching for females, which often remain in hiding on host   dorsal stripe is dark red and intermittent.
            plants. Brephidium exilis disperses northward every summer,
            sometimes reaching as far as Idaho and Manitoba in Canada.
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