Butterflies and moths all have overlapping scales on their two pairs of wings and this is the meaning of their group name, Lepidoptera (lepido = scaley, pteron = wing). Under the scales, the wings are transparent and veined, as in other insects. Another common lepidopteran characteristic is a long sucking proboscis, which is rolled up when not feeding. They have a complete life cycle from egg to larva (caterpillar) to pupa (chrysalis) and then winged, sexually mature adult. The caterpillars have chewing mouthparts, and legs. This is the main feeding stage in the life cycle and some adults do not feed at all.
There are an estimated 200,000 species of lepidoptera worldwide, with many, especially small moths, still undescribed. In general moths are more drably coloured and active at night while butterflies are bright and active by day. However there are many exceptions to this rule. Moths generally have clubbed antennae while butterfies have simpler, straight antennae.
The most primitive groups are the small moths. The oldest fossil for this group comes from the early Cretaceous period, about 100 million years ago. Butterflies in particular developed along with the flowering plants as many feed on flower nectars and are important pollinators.
Lepidopteran taxonomy is quite complicated. There are 24 superfamilies, most of which are small moth groups. The most well known of the moth superfamilies are the Skippers (Hesperoidea) with some 4000 species and the Bombycoidea which includes the hawk moths, the emperor moths and the economically important silk moth.
True butterflies belong to the Papilionoidea, which contains six families and 15,000 species. The Hesperidae contains about 4000 species. These are small to medium sized skippers, with stout bodies, narrow wings and pointed antennae. Their flight is short and darting and many have short 'tails' on the ends of the wings, which may be metallic in colour. There are another 1000 species of Papilionidae which includes the swallowtails, the apollos and the festoons. These are medium to large butterflies with large 'tails' and bright markings.
The third family is the Pieridae, with another 1200+ species. These are called the whites or jezabels, the sulphurs, and the yellows. They are medium-sized butterflies and many are migrants. While most are white or yellow a few are more brightly coloured. The fourth family is the Nymphalidae with about 6000 species. Monarchs, browns, satyrs, tigers and danaids are all nymphalids. They are medium to large and very colourful butterflies. Their forelegs are modified with bristle-like hairs that act as chemical receptors.
The fifth butterfly family is the Riodinidae, with about 1000 species. These are called metalmarks, judies and snout butterflies. They are small to medium sized butterflies. The last butterfly family is the Lycaenidae and is quite large, with about 7000 species. These include the blues and the coppers. They are small butterflies and live predominately in the tropics. The blues often have metallic wing colours.
Although the adult phases are often the most beautiful, it is the caterpillars that are the most important both in the food chain and economically. They also live much longer than the ephemeral adults, whose main purpose is to mate, reproduce and then die. The caterpillars are basically eating machines. Their lives are spent consuming enough plant material to allow for the transformation into an adult. Caterpillars are juicy morsels and many animals, especially birds, include them in their diets. For this reason caterpillars employ a number of defense strategies including camouflage or its opposite,warning colouration combined with acrid taste or poisons. Caterpillars have to moult in order to grow and usually go through about four moults before finally making a chrysalis and pupating. Because they are plant eaters, many caterpillars are pests of economically important crops.
The world would be a much drabber place without these beautiful insects. Nothing signifies a summer day more than a butterfly flitting from flower to flower in the bright sunshine.