enchant creature you control
enchanted creature doesn't untap during your untap step if cocoon has a pupa counter on it.
when cocoon enters the battlefield, tap enchanted creature and put three pupa counters on cocoon.
at the beginning of your upkeep, remove a pupa counter from cocoon. if you can't, sacrifice it, put a +1/+1 counter on enchanted creature, and that creature gains flying. (this effect lasts indefinitely.)