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.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.