I assume they do this to replenish their shield and supporting fleet.
They mature to the next stage after a while, so they go find equipment-module factories and drone factories of the appropriate new mark level to make use of their new abilities.
There are currently about six of those support structures on several planets just behind the front lines and I'm wondering if I should:
A) destroy them, assuming the hybrids will then have to travel further out to repair.
That will do that, yes. They're not "repairing", per se, but yea.
At higher levels they may need to go way back to find a high-enough-mark factory anyway, though.
B) guard them, use them to lure weakened hybrids to this system and destroy them with a strike force as they come in.
You know, I don't think I've ever heard that one before, but I think it would work to kill off new hybrids by clearing out most of the factories and "camping" the remaining ones. I'm not sure how reliably you can guess which one they'll go to based on distance, though. One thing to bear in mind that they don't have to get close to the factories, they just have to get onto the same planet.
C) Ignore them (if they are not important enough)
Killing the support structures is worthwhile (except the construction-module ones unless you're playing on advanced such that the Dyson plot is possible), and killing the hybrid hive spawners on the mkIV+ worlds is very important for reducing the population over time. If you kill all the hive spawners and all the hybrids, they're totally gone.
