Butterfly doesn't spin a cocoon. Caterpillars shed their final skin to reveal a pupa. The outer skin of this pupa hardens to form a chrysalis which protects and hides the amazing transformation that is occurring inside. Pupae take on a wide variety of appearances, depending on the species of butterfly. Some hang from beneath leaves or twigs. Others are girdled to the side of a stem much like a worker on a telephone pole. Some are smooth and shiny while others are rough and even spiky. Some are beautifully colored with dots and lines of gold while others are drab and barely noticeable. No matter what the design, the function is the same - to lessen the chances of being eaten by a predator and to increase the likelihood of producing an adult butterfly or moth.
/http://animalbreed-factstrivia.blogspot.co.at/2010/11/about-butterfly.html/
Polyommatus amandus, Azuré de la jarosse, Amanda's Blue
