Nature: Sex, Lies and Butterflies

Butterflies have been flying around our planet for over 50 million years, and today around 20,000 different species inhabit the globe. From egg to caterpillar to chrysalis to the winged insect, we follow their life stages, highlighting their survival techniques and the new science that is unlocking the secrets of their world and changing our view of these fantastic and yet fragile creatures. (PBS)