The earliest known butterfly fossils are roughly 40 - 50 million years old.

 

Butterflies likely evolved from moths. There are roughly 45,000 species of butterflies (out of a total 220,000 species of Lepidoptera).

 

The image on the right is from a fossil discovered at the Florissant (Colorado) fossil beds. Source: http://www.nps.gov/flfo/photosmultimedia/Insect-and-Plant-Fossils-Gallery.htm