So perhaps the first Xeno of any new event is like Big Chap and in the absence of certain Pheromones, let's say, that indicates a Queen or existing Hive in place, creates a royal egg via eggmorphing.
Then becomes subordinate to the future queen and no longer needs to Egg morph.
Perhaps you could say that in initiating the egg morphing, drone that does this actually sacrifices its self and begins to die due to the effects of creating and egg. This could be a nice nod to the idea that Big Chap was said to be deteriorating in some earlier scripts/drafts.