Lepidoptera

(Moths, Butterflies)

Jerry A. Powell

University of California, Berkeley

Moths and butterflies make up the order Lepidoptera, and they are among the most familiar and easily recognized insects. The Lepidoptera is defined as a monophyletic lineage by a suite of more than 20 derived features, the most obvious of which are the scales and proboscis. The scales are modified, flattened hairs that cover the body and wings, shingle-like, and are the source of the extraordinary variety of color patterns typical of these insects. In all but the most primitive forms, feeding by adults is accomplished by pumping in liquid via a tubular proboscis (haustellum), which usually is elongate and coiled under the head. The sister group of Lepidoptera, the Trichoptera (caddisflies), lack this development of mouthparts and the covering of scales and possess caudal cerci on the abdomen, which are not present in Lepidoptera.

Like other holometabolous insects, lepidopterans pass through egg, larval, pupal, and adult stages. Mating and egg deposition are carried out by the adult moths and butterflies. Within the eggs, embryos develop to fully formed larvae. The larvae, commonly called caterpillars, feed and grow, which is accomplished by a series of stages (instars). At maturity they transform to pupae, usually within silken cocoons spun by the larvae, although many species pupate without a cocoon. Metamorphosis to the adult occurs during the pupal stage, and the fully developed adult breaks the pupal shell to emerge. Adults of most species feed, but they do not grow. Diapause, an arrested state of development, may occur in any of these stages, prolonging life and enabling the insect to bypass seasons that are unsuitable for growth and reproduction.

The Lepidoptera is one of the two or three largest orders of insects, with an estimated 160,000 named species. Based on specimens in collections and extrapolating from recent studies of Central American moths, we believe that fewer than one-half of the known species have been named by

FIGURE 1 Hypothesis of phylogenetic relationships of extant lepidopteran superfamilies. Successively more derived clades representing major morphological changes are indicated in boldface to the left (modified from Kristensen and Skalski, 1999).

taxonomists; even in North America, an estimated one-third of the fauna is undescribed. Thus, a realistic projection of the total world Lepidoptera species number is not possible, but certainly it exceeds 350,000 and may be much larger. Much of this diversity can be attributed to the radiation of species in association with flowering plants. Lepidoptera represent the single most diverse lineage of organisms to have evolved primarily dependent upon angiosperm plants, and their numbers exceed those of the other major plant-feeding insects, Heteroptera, Homoptera, and Coleoptera (Chrysomeloidea and Curculionoidea). Figure 1 depicts the hypothesized evolutionary lineages and lists currently recognized superfamilies of Lepidoptera.

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