Remember the part in book 29, where Cassie is a Yeerk in the Yeerk pool, and she needs to get out, so she just butts her way in front of another Yeerk and takes that guy's host?
Something occurred to me about that scene. Why the heck do they not have safeguards against that very thing? Not just 'Andalite bandits' stealing hosts (since the Yeerks would never guess that they'd ever dare to morph a Yeerk), but other Yeerks doing so. We know that there's pretty fierce competition for hosts, since nearly all Yeerks want one, but there aren't enough to go around. So, what's to stop a Yeerk who wants a host, from just butting in front of another Yeerk trying to get to their host? They obviously don't have a good way of stopping that from happening, since Cassie was able to do it with no problem.
Was she honestly just the first person to think of it? That seems unlikely. Is there a social taboo among Yeerks against taking a host that isn't 'yours'? Also seems unlikely, since Yeerks are instinctually selfish creatures who tend to have the view that if you can take something, you have every right to. Maybe there's a completely separate pool for 'unhosted' Yeerks? Maybe the Yeerks we see in the main Yeerk pool all have a host to call their own, and anybody without a host is kept somewhere else (such as aboard the Pool Ship)? That would at least cut down on incentive to steal a host, but it wouldn't eliminate it entirely, since some hosts are considered more important or valuable than others.
Thoughts? How do Yeerks ever manage to stick with the same hosts long-term, when it's so easy to just pick one you like better and take it instead?