When a caterpillar approaches metamorphosis it starts ramping up hormone ecdysone, sheds its skin like a snake, underneath is a hard shell, like the exoskeleton of a beetle. Then the caterpillar releases enzymes called caspases, which rip apart and dissolve the cells in the caterpillar's muscles, digestive system, and other organs- leaving crucial breathing structures intact (breathing tubes). Special cells called imaginal discs start waking up. These discs were kept dormant in the caterpillars body, once transformation begins, the discs begin to build a butterfly. Each disc contains the genetic recipe to form a different adult body part starting from the inside out. After 1 week the digestive system of the butterfly is intact. by day 16, legs, wings, eyes, and mouth are all present and in working order. each imaginal disc starts off with about 50 cells, they multiply themselves into thousands of cells just to form a single wing. Some chryslisis turns transparent in their final days of transformation. The chrysli splits open down the center, red liquid spills out which is the waste that was created during the process. The wings expand and harden and now butterlfy is ready to mate, pollinate etc.