That's not a bad idea. I know I can have other MM creatures there as slaves of the formians. A new caste or two wouldn't hurt anyone (like a legionnaire caste between warriors and myrmarchs, for example, or a caste built up specifically to handle high-tech weapons or maintain high-tech equipment).
I definitely don't want anyone controlling the formians save the queen. Not sure why, but I think it's nice to have something be simple for a change, without webs of intrigue mucking things up too much. There's enough of that in the Dragonstar galaxy that I have planned... for example, the half-dragon son of that black dragon the PCs killed a few weeks back might just come to Tellene looking for payback, and he'll have an entire backwater world to play with, while the PCs are just now about to get their own ship (which is the point of the formian adventure, after all).
Oh, for those who don't know, Dragonstar is essentially D&D in space. All the D&D classes are there, including the mages and clerics. Basically, science and technology do what they can (machines, powerful weapons, great armor, etc.) and magic does the rest (faster-than-light travel, artificial gravity, etc.). Just in case that helps anyone spawn ideas. In this case, imagine formians with blaster weapons, grenades, and the like.