It's been shown that a Yeerk maintains control when the host morphs, even to extremely small things (When Jake became a controller, he morphed an insect in attempt to escape).
What if the host became a nothlit in a form too small for the Yeerk to escape, or even exist with its mass outside of Z-Space? For instance, if an Animorph became a controller, but say, accidentally became trapped in a glass jar while in fly morph. If the Animorph became a fly nothlit while still a controller, would the Yeek still die of Kandrona starvation?
We know human mass does not get hungry/thirsty, so would the same apply to Yeerks? If it did die, what would happen to its mass? Would it even be possible for the Yeerk to leave the body at this point, or would the Animorph be a controller for the rest of their insect life?
Also, this brings up another topic, which I find more interesting.
If a Yeerk was given the power to morph, and acquired a human, could it become a controller while in morph? Then, when it demorphed, assuming the controlling Yeerk does not die in the scenario questioned above, could you have a Yeerk Controller?
This makes for another interesting scenario. If this Yeerk Controller took a host, would there be three consciousnesses in one body?
What if the new host was a Yeerk morphed as a human? A Yeerk controlling a Yeerk controlling a Yeerk?
If this were possible though, could you technically have an endless chain, to the extent where thousands of Yeerks occupied one body?