butterfly The Columbia Encyclopedia, Sixth Edition | 2008
butterfly any of a large group of insects found throughout most of the world; with the moths , they comprise the order Lepidoptera. There are about 12 families of butterflies. Most adult moths and butterflies feed on nectar sucked from flowers. In the process they may transfer pollen from one flower to another, and many plants depend on moths or butterflies for pollination. Like moths, butterflies have coiled, sucking mouthparts and two pairs of wings that function as a single pair; the wings are covered with scales that come off as dust when the insect is handled.
Butterflies can be distinguished from moths in several ways: the antennae of butterflies are knobbed at the tips, while those of moths almost never have terminal knobs and are often feathery; the body of a butterfly is more slender and usually smoother than that of a moth; butterflies are active by day, while most moths are nocturnal; when at rest most butterflies hold the wings vertically, while most moths flatten them against the surface on which they are resting. The skippers are intermediate in characteristics, but they are usually called butterflies. Some butterflies migrate, usually traveling toward the equator in the fall and away from it in the spring. The North American monarch butterfly makes mass migrations of several thousand miles.
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The Lepidoptera, especially the butterflies, are known for the beautiful colors and patterns of their wings. Red, yellow, black, and white pigments are found in the scales; the blues and greens, and the metallic, iridescent hues found especially in tropical species, are caused chiefly by refraction. Some butterflies are protectively colored to match the environment. Many conspicuously colored species are distasteful to birds, which learn to avoid them, and others are protected by their resemblance to the distasteful species (see mimicry ). Among the most beautiful butterflies are the swallowtails, found all over the world, the monarchs, and the peacock and tortoiseshell butterflies.
Metamorphosis
Metamorphosis is complete, that is, the insect goes through four stages: egg, larva , pupa , and adult. The eggs, which hatch in 2 to 30 days, are usually laid on a plant that the larva (called a caterpillar ) uses for food. Most caterpillars eat leaves. After the last of several molts the larva is transformed into a pupa with a hard, often sculptured outer integument, within which it changes to the adult form. The butterfly pupa is called a chrysalis, or chrysalid. Most chrysalids (unlike the pupae of most moths) are not enclosed in a cocoon; however, they are usually suspended from some object by a silken thread and may have a partial covering. Except in those species that winter in the pupa stage, the adult usually emerges from the integument in two or three weeks. Members of some species winter in the egg stage, others as larvae or adults. The adults of most species, however, live only about a month.
Classification
Butterflies are classified in the phylum Arthropoda, class Insecta, order Lepidoptera. The true butterflies form the superfamily Papilionoidea, and the skippers form the superfamily Hesperoidae.
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butterfly 
