moth, any of the large and varied group of insects which, along with the butterflies, make up the order Lepidoptera. The moths comprise the great majority of the 100,000 species of the order, and about 70 of its 80 families.

The adult moth, like the butterfly, has sucking mouthparts, two compound eyes, and two pairs of wings that function as a single pair and are covered with flattened, dustlike scales. It is distinguished from butterflies by its stouter, usually hairy body and its unknobbed, often feathery antennae. Most moths are nocturnal in their habits, while butterflies are mostly diurnal. A moth flattens its wings against the surface on which it is resting, while most butterflies hold them vertically.

Moths range in size from species with a wingspread of 1⁄6 in. (2 mm) to the Atlas moth with a wingspread of 10 in. (25 cm). Many are protectively colored to match their backgrounds: their patterns may exactly resemble, for example, certain lichens or the bark of certain trees. Many others have large, eyelike markings on the hind wings that are thought to frighten potential predators.

Moths undergo a complete metamorphosis (see insect), from egg through larva and pupa to adult. Moth larvae, or caterpillars, are wingless and wormlike, with a row of simple eyes on either side of the body. They have chewing mouthparts and feed on leaves or other plant material. Many do great damage, such as that of the bee moth, the codling moth, the gypsy moth, the clothes moth, and the cutworm.

The pupa of most moths is protected by a cocoon, built by the larva just before pupating. The cocoon is often made wholly or largely of silk; the cocoon of the domesticated silkworm moth is the source of commercial silk. Some moths make a cocoon of bits of wood or of a leaf, glued together with silk; some pupate underground. During pupation the body form changes to that of the winged adult.

Most adult moths feed on the nectar of flowers, and many plants depend on them for pollination. The short-lived adults of certain species do not eat at all. Among the large and beautiful moths of North America are the cecropia moth, largest of the E United States, and the pale green luna moth.

Moths are classified in the phylum Arthropoda, class Insecta, order Lepidoptera.

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