To Pimp a Butterfly sold 850,000 copies in America by word of mouth.
 Butterflies can only fly when their temperature is above 27 C (81 F); when it is cool, they can position themselves to expose the underside of the wings to the sunlight to heat themselves up
 Several species of butterflies need more sodium than that provided by nectar and are attracted by sodium in salt; they sometimes land on people, attracted by the salt in human sweat

