A butterfly is an insect of the order Lepidoptera. This order includes
the super families like Hedyloidea (the American moth-butterflies ),
Hesperioidea (the skippers) and Papilionoidea (the so-called 'true'
butterflies).Like many Lepidoptera, butterflies are notable for their
unusual life cycle with a larval caterpillar stage, an inactive pupal
stage and a spectacular metamorphosis into a familiar and colorful
winged adult form, and most species being day-flying, they regularly
attract attention.
The Old English word for butterfly was
buttorfleoge apparently because butterflies were thought to steal milk.
A similar word occurs in Dutch and German originating from the same
belief. This is believed to have led to the evolution of its present
name form - butterfly.
Butterflies are nested within the
evolutionary tree of moths. Their origins may date back to the
Cretaceous Period, ending 65 million years ago. Unfortunately, the
fossil record is very limited. The oldest known fossil is an unnamed
possible skipper butterfly from the Upper Palaeocene (around 57 million
year old) of Fur, Denmark. One of the most beautifully preserved is a
Metalmark butterfly (Voltinia dramba) from 25 million year old
Dominican amber.
Butterflies are today distributed throughout
the world except in the very cold and arid regions. There are an
estimated 17,500 species of butterflies (Papilionoidea) out of about
180,000 species of Lepidoptera
Source : http://en.wikipedia.org/wiki/Butterfly