A butterfly is an insect of the Order Lepidoptera, and belongs to one of the superfamilies Hesperioidea (the skippers) or Papilionoidea (all other butterflies). Some authors would include also members of the superfamily Hedyloidea, the American butterfly moths. They are notable for their usual life cycle—proceeding from the larval stage as caterpillars through a pupic metamorphisis into their winged adult form. The patterns formed by their brightly coloured wings and their erratic-yet-graceful flight has made butterfly watching a popular hobby.Butterflies live primarily on nectar from flowers. Some also derive nourishment from pollen, tree sap, rotting fruit, dung, and dissolved minerals in wet sand or dirt. Butterflies play an important ecological role as pollinators.
Antennae shape in the lepidoptera from C. T. Bingham (1905)As adults, butterflies are able to consume liquids only by means of their proboscis. They regularly feed on nectar and sip water from damp patches. This they do for water, for energy from sugars in nectar and for sodium and other minerals which are vital for their reproduction.
Several species of butterflies need more sodium than provided by the nectar they drink from flowers. As such, they are attracted to the sodium in salt (which the males often give to the females to ensure fertility). As human sweat contains significant quantities of salt, they sometimes land on people.
Besides damp patches, some butterflies also visit dung, rotting fruit or carcasses to obtain the essential minerals that they need.
Butterflies sense the air for scents, wind and nectar using their antennae. The antennae come in various shapes and colours. The hesperids have a pointed angle or hook to the antennae.
Some butterflies, such as the Monarch butterfly, are migratory.