That's partly why I listed demographics as a prompt in my comment above. It covers not just the ratio of workers to queens, but the number of births per year, fluctuation in population size, etc. Somewhere in my notes, I have all the numbers I crunched for how to achieve a replacement rate of reproduction. It's easier the more inhuman, or technologically advanced, or *both* your population is. Easiest if they lay eggs, for example, but the idea with the artificial uteruses is to use technological pressure to replicate that effect with IVF. The only story I have up at the moment doesn't touch much on the demographics, though.

Contextual fertility is another good one. You could even use an analog of royal jelly, and have it be a part of a ritualistic selection of the new (emerging) queen. That's ripe for both political play and pageantry. Whereas in my story, not knowing until puberty whether you will be fertile or not has given rise to a cottage industry of charlatans promising to predict the future with superstition or pseudo-science. I will touch on that if I ever get around to writing the school story.