The body of the caterpillar literally melts while it is in a cocoon, and the body of the butterfly is formed anew Bashny.Net

The transformation into a butterfly caterpillars - the process is truly amazing. Imagine being subjected to plastic bottle recycling was melted, and as a result of this material appeared another thing another. Roughly the same thing happens to the caterpillar inside the chrysalis.

Most of the body tracks like "dissolves" and at the bottom of the cocoon formed by the mass of the imaginal discs, which are essentially undifferentiated stem cells. As is known, such cells can form anything - any tissues and organs. However, some parts of the body tracks, such as the legs, yet almost prostrate changes. This process is called a complete conversion golometamorfozom.

The time it takes to convert depends entirely on the type of tracks, but on average lasts about two weeks. In species survive the winter as pupae, conversion can take several months.

via factroom.ru