The pupa or chrysalis
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About the 18th day of the lifecycle, when the caterpillar is 15 days old, it attaches itself to a surface and hangs upside down. Curled up slightly into a "J" position, the caterpillar sheds his skin for the last time, to become a pupa (chrysalis). To accomplish this, the suspended caterpillar twists and turns until the skin behind the head splits. It wriggles the skin down the body and then discards it. Under the caterpillar's last skin is the soft green casing, which takes shape and hardens into a "case" which is the pupa. |
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Inside this casing a mysterious metamorphosis takes place, "shape-shifting" the life form into a butterfly! In the last few days of the pupa stage, the butterfly inside begins to "color up" and the new orange and black on the wings becomes visible. |
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The adult butterfly will emerge from the pupal case in about twelve days. |
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Trivia: the word "Pupa" comes from the Latin, meaning "doll". The Monarch pupa is jade green with shiny gold specks. There are many varieties of Danaus plexippus (Monarchs) in the world, and those from the far East such as the Idea jasoia, have pupae that are completely gold colored, like polished gold! They are beautiful, and this gold coloring helps the pupa by reflecting the vegetation around them, thus making them difficult to see. The American Monarchs feed in more open country than the rain forest species, and natural selection has tended to make them green, and the gold spots are just a vestage from a distant ancestry. |
