My first swarm, two years ago, must have been from a nearby apiary and not a wild colony. The bees were larger and built comb in my foundationless frames around 5.4mm. Since then they have been progressively getting smaller, and now they are little bees, some colonies are darker, while others are golden. It does seem the darker bees are a bit smaller than the others.
I am still measuring cell size, and often it is still 5.4mm, such as this pollen comb below. I need to shake off some brood frames and measure those cells. With all these little bees, it has got to be smaller cell.