Bug Facts:   The beautiful Luna Moth has no mouth. 

Luna Moths along with many of the other Saturniidae Moths only eat in the caterpillar phase.  They eat, eat, eat and fatten up and after they pupate turn into the majestic adult; whose only purpose is to mate.  They mate, pass on their genes to the next generation and since they have no mouth they eventually (usually within a week) starve to death.  A romantic end to a beautiful creature.

*In response to many of the comments:  Yes, it does seem sad and some of you asked why do they even exist? Some said God created them just for us to look at..  These are all interesting hypotheses. If you follow me, you are aware that I am a militant atheist so I disagree with the latter however I am able to supply you with the biological reason for their existence. If you understand it from more of an evolutionary standpoint it seems less tragic.  The “point” of any creature’s existence is to pass on that particular individual’s genes.  Because of this, many adaptations have driven the evolution of said creature’s morphological traits.  Luna Moths, just like all other animals have competition, predation and other factors inhibiting only the strongest to reach the ultimate goal of passing on their genes.  In many insects, the adult form is the shortest lived and main goal is for procreation.  Actually, in many animals, once maturity and siring of offspring is met, the adult phase comes to a close not too soon after the possibility of more offspring is over.  Even in humans, technology and medicine has enabled us to live well passed that age, but biologically speaking most animals are not supposed to outlive the age where they can no longer procreate because that is the biological purpose of ANY creature. Luna Moths just take it one step further and have evolved adult forms without mouths because they were no longer needed.   They still lead interesting lives, eat in one form and mate in another.  In insects especially, it is just the goal and purpose of the adult phase.