I think it would be interesting because Zerg right now suffers from early game ingenuity, forcing them to be reactive most of the time. The other races can proxy unit producing structures and so can take advantage of a late reaction or a bad scouting job with a powerful attack. A moving larva would sort of act like a proxy attack: slow moving larva can easily be scouted, so there is risk in losing it or it in egg form, but there is a slightly better payoff in having zerg units being able to be created from a location near the enemy for an early attack! Think about it. Here are some questions I would have:
-Should the queen have cargo space for larva only?
-Should larva come with this ability or is it researched?
-Can larva crawl off creep or do they die?
-Is larva hiding a skill?
-Is larva counting by Zerg's opponent a new skill that needs to be tuned?
-Should larva be killed easier?
-Moving larva closer to minerals for faster mining when the drone pops: imbalance?
I liked the idea, but of course who knows what will happen to balance. Top Zergs are already deadly, like DRG, stephano, Losira; is this overkill?