Here is a screenshot i took after invading a planet: http://images.akamai.steamusercontent.com/ugc/39750633470478717/140D110AC38D1D10EB1B12D55A166B59C19233BF/
And this is only turn 100. Late game i've seen AIs go to +30 food when the population on the planet is <10. I don't know the exact percentage, but i would say on about 50% of the colonies i conquer i see this kind of farm spamming. I think something is not right here?