simple caterpillars

just a simple caterpillar?

Leaves are good for the tum;
thats what caterpillars think,
they will eat and eat and eat,
until they are so heavy they sink.

But what they can't see,
is that nothing last forever,
that maybe just maybe,
there won't be another.

And when the leaves run out,
and there is no other door,
without a doubt,
the caterpillars will be no more.