Scale-winged insects outnumber almost every other order
Butterflies and moths form Lepidoptera—about one hundred eighty thousand named species, roughly eight point six percent of all described life, second only to beetles among insects. Coloured scales, triangular wings, and a nectar-sipping proboscis define adults that begin as leaf-chewing caterpillars.
Carl Linnaeus used the name in 1746 in Fauna Svecica, from Greek lepis "scale" and pteron "wing." Complete metamorphosis runs egg, caterpillar, pupa, adult. Larvae carry chewing mandibles, three true leg pairs, and up to five pairs of prolegs; many moths wrap silk cocoons, while butterfly pupae harden into chrysalises. Adults uncoil a multi-segment proboscis to drink nectar. Females may lay hundreds of eggs—sources note up to six hundred—usually on host plants their young will eat.
As of 2007 roughly one hundred seventy-four thousand species were listed, with butterflies near seventeen thousand nine hundred fifty and moths the rest. North America holds over seven hundred butterfly and eleven thousand moth species; Australia about four hundred and fourteen thousand. The order skips Antarctica yet climbs from deserts to plateaus: Siberian Apollo flies inside the Arctic Circle in Yakutia near fifteen hundred metres, while Himalayan Apollo forms reach six thousand metres. Wingspans run from millimetre-scale microlepidoptera to more than twenty-five centimetres in Queen Alexandra's birdwing and the Atlas moth.
Fossils appear near the Triassic–Jurassic boundary; coevolution with flowering plants accelerated in the Cretaceous boom. Scales shingle the wings, mixing pigments with structural colour for camouflage, mimicry, and courtship; males may also emit pheromones from them. Some noctuids turn wings into hearing organs. Odd lifestyles abound: sloth moths live in mammal fur, certain Tinea breed on cattle horns, and luna moth adults lack digestive tracts, living a week or so on larval fat. Pollination credits adults; crop losses blame hungry caterpillars—two sides of the same scaled order.
Source: Lepidoptera
