This diagram shows the four stages of complete metamorphosis:
EGG --> LARVA --> PUPA --> ADULT
At the right you see the last three stages of complete metamorphosis for the Monarch Butterfly. First an adult female lays a tiny egg. From this egg hatches a striped caterpillar, which is the Monarch Butterfly's larva, and of course that's the striped critter making his way up the stem. Be sure to check out our caterpillar/larva page.
When the caterpillar grows to a certain point it attaches itself to something like a stem, develops a kind of husk and become the pupa. In the world of butterflies, this pupa has a special name -- chrysalis. Once this "resting stage" ends, the chrysalis "shell" splits, and out comes the winged butterfly, which is the adult stage.
Since most of us learn about insect metamorphosis as early as primary school, it's easy to accept the phenomenon as just the way things are, as something ordinary and to be expected. However, we need to step back and look at this process with fresh eyes. Just imagine: Here we're dealing with the most prolific, in many ways most successful, form of life on earth, and these animals don't grow up the way we do! It's almost as if when a human is born first we're an egg, then we're a dog, then a box of macaroni, and only finally an adult human!
INSECT ORDERS UNDERGOING
Lepidoptera (butterflies & moths)
Hymenoptera (ants, wasps, bees)
Strepsiptera (twist-winged parasites)
Neuroptera (antlions, lacewings)
* Thrips metamorphosis is between simple and complete
Most insects with complete metamorphosis spend most of their lives in a humble, wormy form, doing little more than eating like crazy. Then one day they simply stop eating, go into some kind of daze, and enter their pupal stage, which looks inactive from the outside but which inside is an absolute hurricane of change.
Finally one day this dead-looking thing splits like a ruptured watermelon, and out pops a creature profoundly obsessed with sex!