Asked by Paul Schroeder ^(2,251) 15 days 14 hours ago. (More question by this person)

Why are adult silkmoths born with no mouths or stomachs?

When giant native silkmoths emerge from cocoons they have no mouths or stomachs;why?

Answer from Ben Morrish ^(7,933)
Ben Morrish 15 days 13 hours ago. More questions answered by this person)
   Selected as Best Answer!   
because they don't need them - in the adult stage they just need to reproduce. Once the eggs are fertilized and laid, the adult is no longer needed.

In evolution, the survival of individuals past reproduction isn't selected for unless those individuals are needed to protect / raise the young, or unless they can survive long enough to reproduce again and produce more offspring.

Saving the energy / material that could have been used to produce mouths and stomachs most likely leaves more resources for the silk moth to put into reproduction (perhaps allowing them to produce more eggs / sperm, or to find a mate faster and more efficiently [no need to carry heavy mouth parts of digestive system around]).

Comment from Paul Schroeder ^(2,251) 15 days 11 hours ago.
most excellent analysis

Answer from Gregory Lewis ^(1,502)
Gregory Lewis 6 days 3 hours ago. More questions answered by this person)
We raised silk worms in the fourth grade. I can tell you adult silk moths are not born, they are hatched from silk cocoons. It is the silk worm that is born.

The silk worm is a ravenous eater, and eats only one thing: mulberry tree leaves. It eats enough to sustain it for the rest of its life.