Why Metamorphosis

     We know metamorphosis means changing from one form to another.  We know that most kinds of insects metamorphosis at some point in their life histories.  We know that it is a process that is mysterious and miraculous at once.  How do the insects know what to do?  They don't: They only follow their instincts.  And we know the four stages of complete metamorphosis- eggs, larvae, pupae and adult. 
     The most dramatic, and, probably, best known example of change from one life stage to the next in insects is among the moths and butterflies, particularly the latter grouping.  We know how metamorphosis happens, but we don't know when that phenomena of life began among insects.  And how many people think about what its benefits are, or why it occurs at all?
     As among most species of insects, eggs are the first step of complete metamorphosis.  Among butterflies, the females must lay eggs on certain plants because the caterpillars of each kind of butterfly will eat only one to a few different kinds of plants.  This is unfortunate because if their food plants become extinct, so may the butterfly species dependent on them for food. 
     The caterpillars of each type of butterfly hatch as eating machines, consuming their appointed food almost constantly.  The caterpillars eat and grow rapidly for about two weeks or more, depending on the species, and get bigger and fatter each successive day.
     When each larva can't eat anymore or get any bigger, it stops consuming food altogether and
 forms a protective pupa or cocoon around itself as a shelter where it can change into a butterfly.  The larva becomes dormant, and probably unconscious, as its body cells rearrange themselves to form the butterfly, including with wings.
     When the change of each caterpillar is complete in a few weeks, the butterfly comes out of its stiff pupa.  It perches near its empty chrysalis for a few hours while drying, pumping out and stiffening its wings and otherwise gaining strength for its first flight.
     But what is the advantage of being a winged butterfly?  Each caterpillar eats and grows until full-sized.  It could also become mature as a wingless caterpillar and lay eggs on the plants it just ingested for the next generation of its species.  And, if they did that, there would be no need to waste time and energy in a pupa that is more vulnerable to predation than the caterpillar.  But, perhaps, they ate all the plants of the types they are genetically equipped for.  Now, as winged adults, they must seek proper food plants elsewhere.
     Insects that sip nectar from flowers, as butterflies do, for example, often have to travel over large areas of land to find enough sugary nectar, and dusty pollen, to satisfy their food needs.  And males of each species of butterfly may also have to travel some distance to find a mate to ensure the next generation.  And females of each kind need to travel over acres to find the right plants to lay their eggs on.  Wings are important. 
     Caterpillars, without wings, can't travel like that.  But they can when they become winged adults, the butterflies.  Of course, each larva and its mature form are the same insect, but only the latter form has the ability to fly long distances to find food and mates, thus ensuring the future of its kind.  Caterpillars could never travel far enough, fast enough to save their own species.  So the third stage of complete metamorphosis is important; to provide the quiet, motionless stability needed in little cases of rigid skin (pupae) made by the caterpillars themselves to contain and rearrange body cells to form the mature insect.  And that is why many kinds of insects have that energy-consuming, relatively-risky pupa stage- to mature and grow wings to ensure the next generation of themselves.
     Metamorphosis is miraculous.  When and how it started is a mystery.  But it, and all of nature, is nothing we could create.